vvEPA
United States
Environmental Protection
Agency
Office of Research and
Development
Washington DC 20460
EPA/540/R-98/502
September 1998
Sprinkler Irrigation as a
VOC Separation and
Disposal Method
Innovative Technology
Evaluation Report
SUPERFUND INNOVATIVE
TECHNOLOGY EVALUATION
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EPA/540/R-98/502
September 1998
Sprinkler Irrigation as a
VOC Separation and
Disposal Method
Innovative Technology Evaluation Report
National Risk Management Research Laboratory
Off ice of Research and Development
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
Printed on Recyckd Paper
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Notice
The information in this document has been funded by the U. S. Environmental Protection Agency (EPA) under Contract No.
68-C5-0037 to Tetra Tech EM Inc. It has been subjected to the Agency's peer and administrative reviews and has been
approved for publication as an EPA document. Mention of trade names or commercial products does not constitute an
endorsement or recommendation for use.
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Foreword
The U. S. Environmental Protection Agency (EPA) is charged by Congress with protecting the Nation's land, air, and water
resources. Under a mandate of national environmental laws, the Agency strives to formulate and implement actions leading to
a compatible balance between human activities and the ability of natural systems to nurture life. To meet this mandate, EPA's
research program is providing data and technical support for solving environmental problems today and building a science
knowledge base necessary to manage our ecological resources wisely, understand how pollutants affect our health, and prevent
or reduce environmental risks in the future.
The National Risk Management Research Laboratory is the Agency's center for investigation of technological and manage-
ment approaches for reducing risks from threats to human health and the environment. The focus of the Laboratory's research
program is on methods for the prevention and control of pollution to air, land, water and subsurface resources; protection of
water quality in public water systems; remediation of contaminated sites and groundwater; and prevention and control of
indoor air pollution. The goal of this research effort is to catalyze development and implementation of innovative, cost-
effective environmental technologies; develop scientific and engineering information needed by EPA to support regulatory and
policy decisions; and provide technical support and information transfer to ensure effective implementation of environmental
regulations and strategies.
This publication has been produced as part of the Laboratory's strategic long-term research plan. It is published and made
available by EPA's Office of Research and Development to assist the user community and to link researchers with their clients.
E. Timothy Oppelt, Director
National Risk Management Research Laboratory
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Abstract
Sprinkler irrigation is a common farming practice in those states where the semi-arid climate and lack of sufficient rainfall
during critical growing periods necessitate the use of supplemental water. The source of most irrigation water is groundwater
which can be contaminated with volatile organic compounds (VOCs). Since the groundwater may be the primary or only
source of drinking water for a community, there is a need for reasonable cost-effective treatment and disposal methods.
Typically, groundwater contaminated with VOCs is remediated with conventional pump and treat technologies. The costs
associated with conventional pump and treat options can be significant. Since irrigation is a fairly widespread practice, there
is an opportunity to employ it as a dual purpose technology: crop irrigation and separation and disposal of contaminated
groundwater in order to augment conventional treatment and effect cost savings. Additional benefits of implementation
include containment of the groundwater plume, elimination of discharge or reinfection of the treated groundwater, and reduced
irrigation expense for site vegetative covers.
This premise provided an impetus to evaluate the performance of sprinkler irrigation for these purposes through the conduct of
a SITE program demonstration. This demonstration was conducted by the National Risk Management Research Laboratory
(TSIRMRL) in July 1996 and the final report was completed in August 1997. Results and activities of the demonstration of
sprinkler irrigation technology for the separation and disposal of groundwater contaminated with VOCs are detailed in this
report.
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Contents
List of Figures and Tables vii
Acronyms, Abbreviations, and Symbols viii
Conversion Factors x
Acknowledgments xi
Executive Summary 1
1 Introduction 4
1.1 Background 4
1.2 Superfund Innovative Technology Evaluation Program 4
1.3 Sprinkler Irrigation Technology 4
1.4 Key Contacts 5
2 Technology Applications Analysis 6
2.1 Key Features 6
2.2 Operability of the Technology 6
2.3 Applicable Wastes 6
2.4 Availability and Transportability of the Equipment 7
2.5 Site Requirements 7
2.6 Limitations of the Technology 1
2.6.1 Implementation of the Technology 7
2.7 Applicable or Relevant and Appropriate Regulations (ARARs) for Sprinkler
Irrigation Technology 7
2.7.1 Comprehensive Environmental Response, Compensation,
and Liability Act (CERCLA) 7
2.7.2 National Oil and Hazardous Substances Pollution Contingency Plan (NCP) 8
2.7.3 Clean Air Act (CAA) 8
2.7.4 Clean Water Act (CWA) 8
2.7.5 Safe Drinking Water Act (SWDA) 9
2.7.6 Solid Waste Disposal Act (SWDA) 9
2.7.7 Occupational Safely and Health Administration (OSHA) Requirements 9
2.7.8 State Requirements 9
3 Economic Analy sis 11
3.1 Conclusions and Results of the Economic Analysis
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Contents (continued)
3.1.1 Equipment Costs 11
3.1.2 Labor and Utility Costs 11
3.1.3 Maintenance and Modifications Costs 12
3.1.4 Analytical Services 12
4 Sprinkler Irrigation Technology Effectiveness 13
4.1 Background. 13
4.2 Demonstration Objectives and Approach 13
4.2.1 Demonstration Design 14
4.2.1.1 Sampling and Analysis Program 14
4.3 Sampling and Measurement Locations 15
4.3.1 Sampling and Analytical Methods 16
4.3.1.1 Water Samples 16
4.3.2 Quality Assurance and Quality Control Program 18
4.3.2.1 Field Quality Control Checks 18
4.3.2.2 Laboratory Qulaity Control Checks 18
4.3.2.3 Field and Laboratory Audits 18
4.4 Demonstration Results 18
4.4.1 Operating Conditions 18
4.4.1.1 Sprinkler System Configuration 18
4.4.2 Results and Discussion 33
4.4.2.1 Primary Objective 33
4.4.2.2 Secondary Objectives 34
4.4.3 Data Quality 35
4.4.3.1 Critical Parameters 35
5 References 39
Appendix
A Sprinkler Irrigation Technology Implementation Factors - State Responses
B Process Measurements - Sprinkler Irrigation SITE Demonstration
C Project Objectives for Region 7 Sampling
D Sample Size Estimation
E Statistical Analysis Report
F Risk Assessment
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Figures
1 Sample Point Location Diagram 16
2 Stratified Water Drop Collector 17
Tables
1 Federal and State Applicable or Relevant and Appropriate Regulations (ARARs) 10
2 Installed Costs for Sprinkler irrigation Equipment 12
3 Noncritical Measurements 14
4 Operating and Test Conditions 15
5 Summary Table of Standard Analytical Methods and Procedures 17
6 Percent Removal for VOC Compounds 19
7 Quality Assurance Objectives for Critical Project Measurements 19
8 Hastings Sprinkler Irrigation Demonstration Results - Influent 20
9 Hastings Sprinkler Irrigation Demonstration Results - Height 1 21
10 Hastings Sprinkler Irrigation Demonstration Results - Height 2 22
11 Hastings Sprinkler Irrigation Demonstration Results - Height 3 23
12 Hastings Sprinkler Irrigation Demonstration Results - Height 4 24
13 QC Results for Groundwater Analyses - Duplicates (TCA) 25
14 QC Results for Groundwater Analyses - Duplicates (CT) 26
15 QC Results for Groundwater Analyses - Duplicates (TCE) 27
16 QC Results for Groundwater Analyses - Duplicates (EDB) 28
17 QC Results for Groundwater Analyses - Duplicates (PCE) 29
18 QC Results for Groundwater Analyses 30
19 QC Results for Field Blank Analyses 31
20 QC Results of Trip Blank Analyses 31
21 QC Results of Laboratory Blank Analyses 32
22 Temperature Blanks 33
VII
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Acronyms, Abbreviations, and Symbols
AQCR
AQMD
ARAR
CAA
C C V
CERCLA
CFR
CT
CWA
DCE
EDB
EPA
Gc
ISCST3
k
kPa
MCE
MCLG
MDL
MS
MSD
NAAQS
NDOH
NDEQ
NOAA
NPDES
NRMRL
Micrograms per liter
Air Quality Control Region
Air Quality Management District
Applicable or Relevant and Appropriate Regulations
Clean Air Act
Continuing Calibration Verification
Comprehensive Environmental Response, Compensation, and Liability Act
Code of Federal Regulations
Carbon Tetrachloride
Clean Water Act
1 , 1-Dichloroethene
1,2-Dibromoe thane
U. S. Environmental Protection Agency
Gas Chromatograph
Industrial Source Complex Model
Thousand
Kilopascal
Maximum Contaminant Levels
Maximum Contaminant Level Goals
Method Detection Limit
Matrix Spike
Matrix Spike Duplicate
National Ambient Air Quality Standards
Nebraska Department of Health
Nebraska Department of Environmental Quality
National Oceanic & Atmospheric Administration
National Pollutant Discharge Elimination System
National Risk Management Research Laboratory
viii
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Acronyms, Abbreviations, and Symbols (continued)
ORD Office of Research and Development
OSHA Occupational Safety and Health Administration
PE Performance Evaluation
PCE Tetrachloroethene
POTW Publicly Owned Treatment Works
psi Pound Per Square Inch
QAPP Quality Assurance Project Plan
RCRA Resource Conservation and Recovery Act
RPD Relative Percent Difference
SARA Superfund Amendments and Reauthorization Act
SDWA Safe Drinking Water Act
SE Southeast
SITE Superfund Innovative Technology Evaluation
SW Southwest
SWDA Solid Waste Disposal Act
TCA 1 ,1,1-Trichloroethane
TCE Trichloroethylene
UNL University of Nebraska-Lincoln
v o c Volatile Organic Compound
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Conversion Factors
To Convert From
To
Multiply By
Length
Area:
Volume:
inch
foot
mile
square foot
acre
gallon
cubic foot
centimeter
meter
kilometer
square meter
square meter
liter
cubic meter
2.54
0.305
1.61
0.0929
4,047
3.78
0.0283
Mass:
pound
kilogram
0.454
Energy:
kilowatt-hour
megajoule
3.60
Power:
kilowatt
horsepower
1.34
Temperature: ("Fahrenheit - 32) "Celsius
0.556
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Acknowledgments
This report was prepared under the direction of Ms. Teri Richardson, the EPA SITE technical project manager at the NRMRL
in Cincinnati, Ohio. Contributors to, and reviewers of, this report were Mr. Paul dePercin, Mr. Douglas Grosse, Ms. Rena
Howard, Ms. Ann Kem, Mr. Endalkachew Sahle-Demissie, and Mr. Johnny Springer, Jr. of NRMRL, Mr. Richard Schlenker
of the Nebraska Department of Environmental Quality (NDEQ), and Dr. Roy Spalding, University of Nebraska-Lincoln
(UNL).
The SITE demonstration was conducted as part of the Western Governor's Association initiative on innovative technology and
represents a multi-state collaboration on the review of the sprinkler irrigation remediation and disposal alternative.
The cooperation and participation of the following people are gratefully acknowledged: Mr. Paul dePercin, Mr. Vicente
Gallardo, Ms. Annette Gatchett, Mr. Samuel Hayes, Ms. Ann Kem, Dr. Ronald Lewis, Ms. Kim McClellan, Mr. Randy Parker,
and Ms. Michelle Simon, and Ms. Laurel Staley of NRMRL; Ms. Florence Fulk of EPA National Exposure Research
Laboratory; Ms. Diane Easley, Ms. Hattie Thomas, and Mr. Robert Mournighan of EPA Region 7; Dr. Roy Spalding, UNL;
Mr. Richard Schlenker, NDEQ; and Ms. Rosie Cunningham and Dr. Neal Sellers, Senior Environmental Employee Program-
National Council on Aging.
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Executive Summary
This report summarizes the findings of an evaluation of
sprinkler irrigation as a volatile organic compound (VOC)
separation and disposal method.
Background
A need for lower cost, effective treatment alternatives for
the disposal of treated contaminated groundwater
provided the impetus to conduct a SITE demonstration of
sprinkler irrigation since it provides both separation and
disposal options.
Since the application of irrigation is fairly widespread
throughout the United States, there may be an opportunity
to employ this as a dual purpose technology; concurrent
irrigation and disposal of treated groundwater.
In order to determine whether this option is viable, it is
necessary to address several issues: 1) can the
contaminants be stripped from the groundwater effectively?
2) is irrigation necessary for crop cultivation? 3) are the
increased health risks associated with the air emissions
acceptable? 4) are there state or federal laws which
prohibit the release of the resultant air emissions? and 5) is
this an acceptable alternative to the community?
The results of previous studies conducted by the
University of Nebraska-Lincoln (UNL) concluded that:
irrigation systems can effectively strip VOCs from the
groundwater; stripping efficiencies can be improved to
produce drinking quality water; water is used on site for
beneficial crop needs; capture zones formed will contain
contamination; air emissions will not be a concern; and a
significant savings in resources will result.
In order to provide independent verification of the
technology performance and complement the results
previously reported by UNL, an evaluation was conducted
by the EPA SITE Program in cooperation with EPA
Region 7 and UNL. The demonstration focused on the
technology effectiveness, irrigation requirements, air
emissions, and costs. The technology demonstration was
conducted on July 17,1996 at a contaminated groundwater
site in Hastings, Nebraska.
Sprinkler Irrigation Technology
Sprinkler irrigation is a farming practice that is vital to the
successful production of small grains in central Nebraska
and to the agricultural economy of western states where
the semi- arid climate and lack of sufficient rainfall during
critical growing periods necessitate the use of supplemental
water.
The heart of the irrigation system is the water dispersion
nozzle or sprinkler package. The system that was
evaluated by UNL researchers and the SITE Program was
a center pivot sprinkler equipped with off-the-shelf,
screw-in spray nozzles.
The center pivot is a radial-move pipeline that rotates
around a pivot point. The systems have gained
widespread usage throughout the United States for
agronomic crop production because they are relatively
efficient, low in labor and operating costs, and moderate in
initial cost.
Waste Applicability
Generally, the use of sprinkler systems is reserved for crop
irrigation. However, the need for alternative, lower cost
methods to treat and dispose of treated groundwater has
prompted an investigation of sprinkler irrigation as a
remediation tool.
Previous experience has shown that a high content of iron
and/or calcium may cause clogging of the nozzle openings
and reduce the system effectiveness. Therefore, the
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application of sprinkler irrigation may be limited to
groundwater which does not contain a significant amount
of iron, calcium, sediment, or other material that could
clog the nozzles.
The concentration of VOCs in the groundwater may be a
limiting factor. This determination is made through the
performance of a site-specific risk assessment. Prior to
implementing the technology, a determination of an
inconsequential health risk should be made in accordance
with the applicable federal and state criteria.
A risk assessment was conducted by NDOH prior to the
Demonstration. A determination was made that there
were no consequential health risks associated with
demonstration activities.
Demonstration Objectives and Approach
The SITE demonstration of sprinkler irrigation as a VOC
separation and disposal method was designed with one
primary and four secondary objectives. The selected
objectives are intended to provide potential users of the
technology with sufficient information to assess the
appropriateness and applicability of sprinkler irrigation
for separation and disposal of contaminated groundwater
at other sites.
Primary Objective:
Determine the efficacy of the sprinkler irrigation system to
treat groundwater contaminated with VOCs to
concentrations that average below the maximum
contaminant limits (MCLs); specifically, Trichloroethylene
(TCE), Carbon tetrachloride (CT), and Tetrachloroethene
(PCE) to 5 ug/L, 1,2-Dibromoethane (EDB) to 0.05 ug/
L), and 1,1,1-Trichloroethane (TCA) to 200 ug/L at a
95% confidence level.
Secondary objectives:
Determine costs associated with the
application of the technology.
Evaluate air emissions risks using the industrial source
complex model (ISCST3).
Calculate the average percent removal of critical VOCs in
the sprinkler mist.
Calculate the average percent removal of critical VOCs at
the lowest sampling height during the last sampling run.
The demonstration objectives were achieved through the
collection and analysis of water emitted from the sprinkler
(i.e effluent). These samples were collected July 17,1996
in accordance with an approved quality assurance project
plan (QAPP) dated July 10,1996.
Demonstration Conclusions
Based on the sprinkler irrigation demonstration results,
the following conclusions can be made:
The results of data from all sampling heights
indicate that the mean effluent concentration of
TCA, CT, and PCE were less than the MCLs.
For EDB and TCE, the mean concentration was
significantly greater than the MCLs.
The cost to install a sprinkler irrigation system
is estimated to range from $58,000-$97,000.
Operation and maintenance costs were estimated
to be $35,000/year.
Air emissions analysis indicated that there were
no related health risks associated with the use of
the technology at the demonstration site.
Overall, the reduction of individual VOCs in
groundwater ranged from approximately
95.4 % to 97.6 %.
At the lowest sampling height (HI), the percent
removal ranged from 96.1 to 98.9%.
The results of data from the lowest sample
collection height indicate that the mean concen-
tration of TCA, CT, and PCE were well below
the MCLs. For TCE, the mean concentration of
TCE was shown to be significantly greater than
the MCL. The data collected provided no
indication that the mean concentration of EDB
was significantly larger than the MCL.
Technology Applicability
Sprinkler irrigation was evaluated to identify its
advantages, disadvantages, and limitations as a remediation
option for the separation and disposal of VOCs in
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groundwater. The overall effectiveness of the system
depends on several factors which include system design,
water quality, contaminant properties, nozzle aperture,
nozzle pad design, water pressure, and ambient
conditions.
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Section 1
Introduction
1 .1 Background
This report documents the findings of an evaluation of
sprinkler irrigation as a VOC separation and disposal
method. This evaluation was conducted by the EPA SITE
Program in cooperation with EPA Region 7 and the
University of Nebraska-Lincoln (UNL). The sprinkler
irrigation demonstration was conducted on July 17,1996
at a contaminated groundwater site located in Hastings,
Nebraska.
The demonstration was performed to determine the
efficacy of the sprinkler irrigation system to treat and
dispose of groundwater contaminated with VOCs to
concentrations that average below the MCL; specifically,
TCA (200 ug/L), TCE (5 ug/L), CT (5 ug/L), EDB (0.05
ug/L), and PCE (5ug/L). The MCL for each contaminant
was established by Region 7 as the threshold level
appropriate to determine the ability of sprinkler irrigation
to meet drinking water standards.
The water sampling was conducted by U.S. EPA Office of
Research and Development (ORD), EPA Region 7, and
UNL personnel. All sample analyses were performed by
U.S. EPA ORD, Cincinnati, Ohio. All demonstration
activities were conducted in accordance with an approved
quality assurance project plan (QAPP) dated July 10,
1996.
This report provides information about the sprinkler
irrigation demonstration that is useful to remedial
managers, environmental consultants, and other potential
users in implementing the technology at contaminated
sites. Section 1.0 presents an overview of the SITE
Program, describes the sprinkler irrigation technology,
and lists key contacts. Section 2.0 presents information
relevant to the technology's application, applicable
wastes/contaminants, key features of the technology, site
support requirements, and limitations of the technology.
Section 3.0 presents information on the costs associated
with applying the technology. Section 4.0 presents
information relevant to the technology's effectiveness,
including site background, demonstration procedures, and
the results and conclusions of the demonstration. Section
5.0 lists references used in preparing this report.
1.2 Superfund Innovative Technology
Evaluation Program
The SITE Program was created in order to develop,
demonstrate, and establish the commercial potential of
innovative technologies for treating wastes found at
Superfund and other hazardous waste sites across the
country. Through SITE Demonstrations, the EPA
acquires the cost and performance data necessary to
properly consider innovative technologies in the remedial
action decision-making process. If successfully tested,
these technologies may become alternatives to land
disposal or other less desirable forms of remedial action.
1.3 Sprinkler Irrigation Technology
Sprinkler irrigation is a farming practice that is vital to the
successful production of small grains in central Nebraska
and to the agricultural economy of western states where
the semi- arid climate and lack of sufficient rainfall during
critical growing periods necessitate the use of supplemental
water.
The system that was evaluated by UNL researchers was a
center pivot sprinkler equipped with off-the-shelf, screw-
in spray nozzles. The center pivot sprinkler consists of a
radial-move pipeline that rotates around a pivot point.
The arm of the sprinkler system can be short or long,
depending on the availability of water and land.
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The nozzles were configured to have a small opening from
which a stream of water is emitted. The high velocity
stream strikes an impact pad and forms a thin film of water.
The film breaks into small droplets as it leaves the pad.
The droplet size depends on the pressure and the impact
pad design.
Sprinkler irrigation systems have gained widespread
usage throughout the United States for agronomic crop
production because they are relatively efficient, low in
labor and operating costs, and moderate in initial
investment cost.
1.4 Key Contacts
Additional information about the sprinkler irrigation
technology and the SITE Program can be obtained from
the following sources:
The SITE Program
Ms. Annette Gatchett
Associate Director of Technology
U.S. Environmental Protection Agency
National Risk Management Research Laboratory
26 W. Martin L. King Drive
Cincinnati, OH 45268
Phone: (513)569-7697
FAX: (513)569-7620
E-mail: gatchett.annette@epamail.epa.gov
Sprinkler Irrigation SITE Demonstration
Ms. Teri Richardson
U.S. Environmental Protection Agency
National Risk Management Research Laboratory
26 W. Martin L. King Drive
Cincinnati, OH 45268
Phone:(513)569-7949
FAX: (513)569-7105
E-mail: richardson.teri@epamail.epa.gov
Mr. Paul dePercin
U.S. Environmental Protection Agency
National Risk Management Research Laboratory
26 W. Martin L. King Drive
Cincinnati, OH 45268
Phone:(513)569-7797
FAX: (513)569-7105
E-mail:depercin.paul@epamail.epa.gov
Center Pivot Sprinkler Irrigation
Dr. Roy Spalding
University of Nebraska
Water Center/Environmental Programs
103 Natural Resources Hall
P.O. Box 830844
Lincoln, NE
Phone: (402)472-7558
FAX: (402)472-9599
Nebraska State Participation
Mr. Richard Schlenker
Nebraska Department of Environmental Quality
P.O. Box 98922
1200 N. Street
Lincoln, NE 68509-8922
Phone: (402)471-3388
FAX: (402)471-2909
EPA Region 7 Cleanup at the Hastings Site
Ms. Diane Easley
SUPRIANE
U.S. EPA Region 7
726 Minnesota Avenue
Kansas City, KS 66101
Phone:(913)551-7797
FAX: (913)551-7063
E-mail: easley.diane@epamail.epa.gov
Quality Assurance/Quality Control
Ms. Ann Kern
U.S. Environmental Protection Agency
National Risk Management Research Laboratory
26 W. Martin L. King Drive
Cincinnati, OH 45268
Phone: (513)569-7635
FAX: (513)569-7585
E-mail: kern.ann@epamail.epa.gov
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Section 2
Technology Applications Analysis
The analysis is based primarily on the results of this SITE
demonstration, research conducted by UNL, and data
compiled by EPA Region 7.
The results of studies conducted previously by UNL
concluded that 1) sprinkler irrigation technology can
effectively strip VOCs from the groundwater, 2) stripping
efficiencies can be improved to produce drinking quality
water, 3) water is used on-site for beneficial crop needs, 4)
capture zones formed will contain contamination, 5) air
emissions will not result in increased health risks, and 6) a
savings of resources will occur.
2.1 Key Features
Sprinkler irrigation is widely used throughout the United
States and the world for crop production for the purpose of
irrigating sandy areas and hilly terrains. These systems are
self-propelled, highly mechanized, and efficient. In
addition, they apply water uniformly, have low labor and
operating requirements, do not require land leveling, and
start-up costs are not excessive.
The key component of the irrigation system is the water
dispersion nozzle or sprinkler package. By placing
sprinkler nozzles at relatively close intervals along an
elevated pipeline, field water application is, essentially,
uniform.
Systems vary in length, from 35 m (115 ft) to more than
914 m (2998 ft) depending on site conditions and the
availability of water.
The use of a sprinkler irrigation system for separation and
disposal of VOC-contaminated groundwater may be
advantageous; especially at locations where crop
irrigation is required.
The performance of sprinkler irrigation as a remediation
technique primarily depends upon the system configuration,
water quality, contaminant, spray nozzle aperture, and
ambient conditions. Contaminated water is extracted and
pumped through a pipeline onto an impact pad. After
striking the impact pad a thin film is formed which breaks
into small droplets creating a mist as it leaves the pad.
There are no residual wastes generated as a result of this
treatment..
Since irrigation is a widespread practice, the ability to have
it serve a dual function, irrigation and separation/disposal,
can significantly reduce clean-up costs at "select" sites.
2.2 Operability of the Technology
Sprinkler irrigation is simple to operate. It consists of an
elevated pipeline with sprinkler nozzles spaced at
relatively close intervals. The system can be transportable
and moved from site to site.
Water is generally pumped from an aquifer to the pipeline
at a rate of 0.7-1 .1 ft3/min/acre (5-8 gal/min/acre). The
operating pressure ranges from 103 to 483 kPa (15-70 psi).
The stripping efficiency of VOCs can be affected by
weather conditions such as temperature, humidity, and
wind speed.
For the SITE demonstration, three one-hour test runs were
conducted in order to obtain a representative evaluation of
the system performance.
2.3 Applicable Wastes
Sprinkler irrigation may be applicable to any contaminant
that can be effectively stripped from the groundwater
(primarily VOCs). For example, the water treated during
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the SITE demonstration was contaminated with TCE, CT,
EDB, TCA, and PCE.
The utilization of sprinkler irrigation as a remediation tool
was driven, in part, by the need to find more cost- effective
methods for contaminated groundwater treatment.
Standard remediation options include pump-and-treat and
air sparging. Although these technologies can effectively
remove volatile contaminants from the groundwater, the
costs are substantially high. In those regions of the country
where groundwater contamination is wide spread, the cost
to clean up the water supply can be sizable. The use of
irrigation to remove these contaminants could potentially
reduce or eliminate the need for more expensive treatment
options.
The determination of a waste's suitability for treatment is
made on an a site specific basis through site
characterization and treatability testing.
2.4 Availability and Transportability of
the Equipment
Sprinkler irrigation equipment is commercially available
from a number of manufacturers. The system is designed
to be mobile.
2.5 Site Requirements
The main site requirement for use of sprinkler irrigation is
topography with a slope less than 15% and adequate
surface drainage.
If an electric drive unit is used, a generator or other source
of electricity must be available at the site.
2.6 Limitations of the Technology
When used in tandem with crop irrigation, the effective
remediation period is limited to the irrigation season. For
western and central U.S. states, the typical irrigation
season is from June until September. In other states, such
as Florida, irrigation may be performed year round.
Rainfall or a low temperature could impact optimal
results.
2.6.1 Implementation of the Technology
Implementation of the sprinkler irrigation technology will
differ from site to site. In order to determine the feasibility
of implementing the technology at a specific site, a
number of issues should be addressed. These include, but
are not limited to, the following: appropriateness of the
location, groundwater pumping rate, containment of the
groundwater plume, effect on crop production, applicable
state regulations, air emissions modeling and monitoring,
operational concerns, recharge to an aquifer, and
applicable wastes.
These issues were posed to state reviewers during the
planning phase of the demonstration activities. A
summary of the responses is provided in Appendix A.
2.7 Applicable or Relevant and
Appropriate Regulations (ARARs)
for Sprinkler Irrigation Technology
ARARs that pertain to the transport, storage, and disposal
of wastes generally do not apply because the source of
contamination is assumed to be an aquifer and there are no
anticipated disposal wastes.
Federal and state ARARs are presented in Table 1. These
regulations are reviewed with respect to the demonstration
results. State and local regulatory requirements, which
may be more stringent, must also be addressed by remedial
managers. ARARs may include the following: (1) the
Comprehensive Environmental Response, Compensation,
and Liability Act; (2) the National Oil and Hazardous
Substances Pollution Contingency Plan; (3) the Clean Air
Act; (4) the Clean Water Act; (5) the Safe Drinking Water
Act; (6) the Solid Waste Disposal Act; and (7) the
Occupational Safety and Health Administration regulations.
These general ARARs are discussed below.
2.7.1 Comprehensive Environmental
Response, Compensation, and
Liability Act (CERCLA)
The CERCLA of 1980 as amended by the Superfund
Amendments and Reauthorization Act (SARA) of 1986
provides for federal funding to respond to releases or
potential releases of any hazardous substance into the
environment, as well as to releases of pollutants or
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contaminants that may present an imminent or significant
danger to public health and welfare, or to the environment.
As part of the requirements of CERCLA, the EPA has
prepared the National Oil and Hazardous Substances
Pollution Contingency Plan (NCP) for hazardous
substance response. The NCP is codified in Title 40 Code
of Federal Regulations (CFR) Part 300, and delineates the
methods and criteria used to determine the appropriate
extent of removal and cleanup for hazardous waste
contamination.
SARA states a strong statutory preference for innovative
technologies that provide long-term protection and directs
EPA to do the following:
use remedial alternatives that permanently and
significantly reduce the volume, toxicity, or
mobility of hazardous substances, pollutants, or
contaminants;
select remedial actions that protect health and
the environment, are cost- effective, and involve
permanent solutions and alternative treatment or
resource recovery technologies to the maximum
extent possible; and
avoid off site transport and disposal of untreated
hazardous substances or contaminated materials
when practicable treatment technologies exist
[Section 121(b)].
2.7.2 National Oil and Hazardous
Substances Pollution Contingency
Plan (NCP)
The NCP is required by section 105 of the CERCLA of
1980,42 U.S.C. 9605, as amended by the SARA of 1986,
Pub.L.
The purpose of the NCP is to provide the organizational
structure and procedures for preparing for and responding
to discharges of oil and releases of hazardous substances,
pollutants, and contaminants.
The NCP applies to and is in effect for (1) discharges of oil
into or on the navigable waters of the United States, on the
adjoining shorelines, the waters of the contiguous zone,
into waters of the exclusive economic zone, or that may
affect natural resources belonging to, appertaining to, or
under the exclusive management authority of the United
States and (2) releases into the environment of hazardous
substances, and pollutants or contaminants which may
present an imminent and substantial danger to public
health or welfare of the United States.
2.7.3 Clean Air Act (CAA)
The CAA establishes national primary and secondary
ambient air quality standards for sulfur oxides, particulate
matter, carbon monoxide, ozone, nitrogen dioxide, and
lead. It also limits the emissions of 189 listed hazardous
pollutants such as arsenic, asbestos, benzene, and vinyl
chloride. States are responsible for enforcing the CAA.
To assist in this, Air Quality Control Regions (AQCR)
were established. Allowable emissions are determined by
the AQCR, or its sub-unit, the Air Quality Management
District (AQMD). These emission limits are determined
based on whether or not the region is currently within
attainment for National Ambient Air Quality Standards
(NAAQS).
The CAA requires that treatment, storage, and disposal
facilities comply with primary and secondary ambient air
quality standards. Emissions from the sprinkler irrigation
technology may come from the effluent water mist which
may contain small amounts of VOCs. The maximum
allowable air emissions are determined by each state on a
case-by-case basis.
2.7.4 Clean Water Act (CWA)
The objective of the CWA is to restore and maintain the
chemical, physical, and biological integrity of the nation's
waters. To achieve this objective, effluent limitations of
toxic pollutants from point sources were established.
Publicly owned treatment works (POTWs) can accept
waste water with toxic pollutants; however, the facility
discharging the waste water must meet pre-treatment
standards and may need a discharge permit. A facility
desiring to discharge water to a navigable waterway must
apply for a permit under the National Pollutant Discharge
Elimination System (NPDES). When an NPDES permit is
issued, it includes waste discharge requirements for
volumes and contaminant concentrations.
In its dual function as an irrigation system and separation
technology, the sprinkler irrigation system does not
generate any waste streams that would be regulated by the
-------
CWA. Therefore, the CWA was not an ARAR for the
sprinkler irrigation technology.
2.7.5 Safe Drinking Water Act (SD WA)
The SDWA of 1974, as most recently amended by the Safe
Drinking Water Amendments of 1986, requires the EPA to
establish regulations to protect human health from
contaminants in drinking water. The legislation
authorized national drinking water standards and a joint
federal-state system for ensuring compliance with these
standards.
The National Primary Drinking Water S tandards are found
in 40 CFR Parts 141 through 149. These drinking water
standards are expressed as maximum contaminant levels
(MCLs) for some constituents and maximum contaminant
level goals (MCLGs) for others. Under CERCLA (Section
121(d)(2)(A)(ii)), remedial actions are required to meet
the standards of the MCLGs when relevant.
For the sprinkler irrigation demonstration, EPA Region 7
established the MCLs for each contaminant present in the
groundwater, in accordance with the SDWA mandate.
2.7.6 Solid Waste Disposal Act (S WDA)
The Solid Waste Disposal Act, which was passed by
Congress in 1965, was the first federal law to require
safeguards and encourage environmentally sound methods
for disposal of household, municipal, commercial, and
industrial refuse. This law was amended in 1970 by the
Resource Recovery Act and again in 1976 by the Resource
Conservation and Recovery Act (RCRA). The primary
goals of RCRA are to protect human health and the
environment from potential hazards of waste disposal,
conserve energy and natural resources, reduce the amount
of waste generated, including hazardous waste, and 4)
ensure that wastes are managed in an environmentally
sound manner.
The use of sprinkler irrigation for the separation and
disposal of VOCs is an environmentally sound remedial
option because it relies on an existing process application
and there are no additional wastes streams generated. In
addition, the use of sprinkler irrigation would result in a
significant conservation of energy and natural resources.
2.7.7 Occupational Safety and
Health Administration (OSHA)
Requirements
CERCLA remedial actions and RCRA corrective actions
must be performed in accordance with the OSHA
requirements detailed in 20 CFR Parts 1900 through 1926,
especially §1910.120 which provides for the health and
safety of workers at hazardous waste sites. State OSHA
requirements, which may be significantly stricter than
federal standards, must also be met.
All personnel operating the sprinkler irrigation system or
collecting samples at a hazardous waste site are required to
have completed an OSHA training course and must be
familiar with all OSHA requirements relevant to
hazardous waste sites. Workers on hazardous waste sites
must also be enrolled in a medical monitoring program.
The elements of any acceptable program must include: (1)
a health history, (2) an initial exam before hazardous waste
work starts to establish fitness for duty and a medical
baseline, (3) periodic (usually annual) examinations to
determine whether changes due to exposure may have
occurred and to ensure continued fitness for the job, (4)
appropriate medical examinations after a suspected or
known exposure, and (5) an examination at termination.
For most sites, minimum personal protective equipment
for workers will include gloves, hard hats, safety glasses,
and steel-toe boots. Depending on contaminant types and
concentrations, additional PPE, including respirators or
supplied air, may be required.
2.7.6 State Requirements
In many cases, state requirements supersede the
corresponding federal program, such as OSHA or RCRA,
when the state program is federally approved and the
requirements are more strict.
-------
Table 1. Federal and State Applicable or Relevant and Appropriate Regulations (ARARs) for Sprinkler Irrigation Technology
Process ARAR
Activity
Waste
characterization of
untreated waste
Description of
Regulation
Standards that
apply to
identification and
characterization of
wastes
General
Applicability
Chemical and
physical analyses
must be performed
to determine if
waste is a
hazardous waste.
Specific
Applicability
to Sprinkler
Irrigation
Chemical and
physical properties
of waste determine
its suitability for
treatment by
sprinkler irrigation
Waste processing
CAA: 40 CFR Part
50 (or state
equivalent)
CERCLA: 40 CFR
Part 300
Determination of
cleanup standards
SARA: Section 121
SDWA: 40 CFR
Part 141
Regulation governs
toxic pollutants,
visible emissions,
and particulates.
NA
Regulation states a
strong preference
for innovative
technologies that
provide for long-
term protection.
NA
Standards that
apply
to groundwater
sources that may be
used as drinking
water.
Remedial actions of
groundwater are
required to meet
maximum
contaminant
level goals
(MCLGs)
or maximum
contaminant levels
(MCLs) established
under SDWA.
During sprinkler
irrigation treatment
the concentration of
VOCs in the effluent
mist must not
exceed limits set for
the air district of
operation.
Standards for
monitoring and
record keeping may
apply.
Sprinkler irrigation
is a low-cost,
innovative
remediation and
disposal method
that can be used to
significantly reduce
the toxicity, volume,
or mobility of VOCs
in groundwater.
The effluent must
be analyzed to
determine
compliance with
MCLs.
10
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Section 3
Economic Analysis
The costs associated with this technology are identified in
the 12 cost categories defined by EPA that reflect typical
cleanup activities encountered on Superfund sites. These
include 1) site and facility preparation, 2) permitting and
regulatory requirements, 3) equipment, 4) startup and
fixed, 5) labor, 6) consumables and supplies, 7) utilities, 8)
effluent separation and disposal, 9) residuals and waste
shipping and handling, 10) analytical services, 11) facility
modifications and maintenance, and 12) site
demobilization.
3.1 Conclusions and Results of the
Economic Analysis
The primary purpose of this economic analysis is to
provide a cost estimate for application of sprinkler
irrigation as a remedial tool in tandem with crop irrigation.
The cost categories relevant to the application of this
technology include equipment, labor, utilities, analytical
services, and maintenance and modifications. Other cost
categories that typically apply for site remediations may
not be significant for sprinkler irrigation and, therefore,
are not addressed in this report. These include site
preparation, permitting and regulatory requirements,
startup and fixed, consumables and supplies, effluent
separation and disposal, residuals and waste shipping and
handling, and site demobilization.
Labor and utility costs are based on estimates for crop
production in Florida, and are provided for reference only.
Cost estimates for these categories will require
adjustments to reflect regional wages, utility rates, and
crop. The estimates for labor and utility assume an annual
pumpage of 10-25 inches of water and 40-500 acres (1.1 -
34 million gallons) coverage for a center pivot irrigation
unit.
3.1.1 Equipment Costs
The major piece of equipment is a commercial irrigation
unit, sized according to the acreage to be irrigated.
Support equipment refers to pieces of purchased or leased
equipment that will only be used for one project, or
optional items that can be used with the irrigation unit (i.e.-
pressure transducer, ram shutoff, flowmeters, surge
protectors, gear motors).
The capital cost of the irrigation unit varies according to
size. The approximate cost for three different units
(including installation and freight costs) is given in Table
2. The estimated costs assume transport of the irrigation
equipment from the manufacturer's facility to the
Hastings contaminated groundwater site (approximately
150 miles). Freight costs will vary, depending on the site
location. For the purpose of these cost estimates, it is also
assumed that the irrigation equipment can be tied into
water and electrical supplies at the site.
3.1.2 Labor and Utility Costs
Based on the annual pumpage estimates, the labor costs
range from 2 -1250 man-hr (0.05 - 0.1 man-hr/ac-inch).
Anticipated utility costs that will be incurred are
associated with pumping. Estimated pumping costs range
from approximately $400 - $22,000 ($1.00 - $1.75/ac-
inch). The costs will vary depending on the year, crop,
location, and fuel source. Typical fuel sources include
electricity, gasoline, propane, and diesel fuel.
In addition, the cost to pump the groundwater from the
plume to the surface must also be included.
The total treatment cost for a 980 ft unit is estimated to be
$0.07-0.09/gallon (assumes a labor rate of $10 -20/hour).
11
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Table 2. Installed Costs for Sprinkler Irrigation Equipment
Unit Installed Analytical Sub
Size Acres Cost Tests* Total cost**
jft)
660 31 $56,000 $1,000 $57,000 $58,000
980 69 $73,000 $2,000 $75,000 $77,000
1300 122 $92,000 $3,000 $95,000 $97,000
Notes:
* To determine the content of VOCs in the water.
** Cost indexed for inflation (1997 dollars).
3.1.3 Maintenance and Modifications
costs
Labor costs and the cost of replacement parts are the major
maintenance and modifications costs.
Basic maintenance for irrigation systems include flushing
water lines and checking valves and sprinklers, examining
valves to ensure they work properly, flushing irrigation
lines to remove any sediment which may have
accumulated and could clog sprinklers, and checking
nozzles for wear. The systems should also be evaluated for
proper water pressure, application rate, and application
depth.
3.1.4 Analytical Services
Sampling and analysis of the system effluent may be
performed on a routine basis to ensure proper performance
and compliance with regulatory limitations, if stipulated.
12
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Section 4
Sprinkler Irrigation Technology Effectiveness
4.1 Background
The sprinkler irrigation SITE demonstration was
conducted at a location down gradient from two subsites,
Far-Mar-Co and North Landfill, which are part of the
Hastings groundwater contamination site. This location is
on the eastern edge of Hastings, Nebraska. The 20-ha (50
acre) experimental site is a furrow-irrigated corn field
underlain by commingled plumes of contaminated
groundwater. The groundwater is approximately 36.5 m
(120 ft) below the land surface and is primarily
contaminated with TCE, TCA, 1,1 -Dichloroethene
(DCE), cis-U-DCE, PCE, CT, and EDB. The Far-Mar-
Co subsite is the up gradient source for the CT, EDB, and
TCA. The North Landfill subsite is the primary source for
TCE, DCE, and PCE.
4.2 Demonstration Objectives and
Approach
Demonstration objectives were selected to provide
potential users of sprinkler irrigation technology with the
necessary technical information to assess the applicability
of the system to other contaminated sites.
One primary and four secondary objectives were selected
as evaluation criteria. These objectives are summarized
below:
Primary objective:
Determine the efficacy of the sprinkler irrigation
system to treat groundwater contaminated with
VOCs to concentrations that average below the
MCLs; specifically, TCE, CT, and PCE to 5 ug/
L, EDB to 0.05 ug/L, and TCA to 200 ug/L at a
95% confidence level.
TCE, CT, PCE, EDB, and TCA were determined to be the
contaminants that pose the most significant concern.
The primary objective was achieved by collecting
representative samples of the mist emitted from the pivot
arm during three test runs. The effluent VOC
concentrations for critical VOCs were evaluated.
Secondary objectives:
Determine costs associated with the application
of the technology.
Evaluate air emissions risks using the ISCST3.
Calculate the average percent removal of critical
VOCs in the sprinkler mist (all heights).
Calculate the average percent removal of critical
VOCs at the lowest sampling height. (Note: The
last sampling run was chosen to evaluate this sec-
ondary objective to reduce the number of addi-
tional sample analyses required of the laboratory.
Four samples at the lowest sampling height were
collected to evaluate the primary objective. There
fore, an additional eight samples were collected
and analyzed to meet this secondary objective.)
The secondary project objectives and the associated
noncritical measurement parameters required to achieve
them are listed in Table 3.
To meet the demonstration objectives, data were collected
and analyzed using the methods and procedures
summarized in the following section.
13
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Table 3. Noncritical Measurements
Secondary Objective
Measurement Parameter
Determine costs associated with the application of
the technology.
Evaluate air emissions risks using the ISCST3.
Calculate the average percent removal of critical
VOCs in the sprinkler mist.
Calculate the average percent removal of critical
VOCs at the lowest sampling height during the
last sampling run.
Commercial treatment costs including capital
equipment, labor, utility, maintenance, and
analytical costs.
Effluent VOC concentrations, ambient
temperature, and wind speed and direction.
Influent and effluent VOC concentration for critical
VOCs.
Influent and effluent VOC concentrations from
lowest sampling height samples during last
sampling run.
4.2.1 Demonstration Design
This section describes the demonstration design, sampling
and analysis program, and sample collection frequency
and locations. The purpose of the demonstration was to
collect and analyze samples of known and acceptable
quality to achieve the primary objective stated in Section
4.2.
The demonstration was comprised of three separate
sampling events. Each event was conducted approximately
for one hour after the system had reached a constant water
pressure of 241 Kpa (35 ± 1 psi). Each event consisted of
start up, attainment of a constant pressure, one hour of
constant pressure operation (when sampling occurred),
and shut down.
Test conditions (i.e.- wind speed and direction, air
temperature) were those that existed at the time of testing
since they could not be directly controlled. Each test
consisted of three one hour runs. Therefore, the total
evaluation period was three operating hours. The runs
took place at approximately 9:30 a.m., 2:00 p.m., and 6:00
p.m. The average hourly test conditions for air
temperature, humidity, pH, flowrate, pressure, and water
temperature represent an average of four measurements
(one measurement every 15 minutes). Measurements for
barometric pressure, wind direction, and wind speed were
taken twice per hourly run.
The test conditions are summarized in Table 4.
The technology demonstration incorporated two operating
parameters, pressure and flowrate, that were established
by the UNL during past operations.
4.2.1.1 Sampling and Analysis Program
The objective of the sampling program was to collect
sufficient data to evaluate the sprinkler irrigation system
for the specific objectives outlined in Section 4.2.
The strategy employed to meet the sampling objectives
was to:
Collect VOC samples and take measurements at
the influent and effluent streams during each
one hour sampling run.
Measure the total volume of water that flowed
into the system during each sampling event
(required for the air dispersion model).
All parameters associated with the critical objective were
designated as critical measurements and required
sufficient quality control (QC) to ensure that reliable and
reproducible data were obtained.
Prior to collecting the initial sample for each sampling
event, the irrigation well and transmission lines between
the well and the pivot were purged completely and the well
14
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Table 4. Operating and Test Conditions
Process
Measurement
Air Temperature," F
Barometric Pressure,
mm Hg
Humidity, %
PH
Water Flowrate, gpm
Water Pressure, psi
Water Temperature, °F
Wind Direction
Wind Speed, mph
Measurement
Frequency
Every 15 minutes
One hour intervals
Every 15 minutes
Every 15 minutes
Every 15 minutes
Every 15 minutes
Every 15 minutes
One hour intervals
One hour intervals
Condition 1 1
80
29.83
76
7.10
1150
34
58.9
170 (SE)
170 (SE)
10
Condition 2 1
91
29.81
63
*
1150
35
59.4
190(SW)
170 (SE)
9.5
Condition 3 1
94
29.79
61
7.09, 8.55**, 6.57
1150
34
59.6
190 (SW)
Variable
5.5
Notes:
1 Raw data for process measurements are provided in Appendix B.
* pH meter was not functioning properly.
** Meter was recalibrated at pH 7 after an unusually high groundwater reading was observed.
was pumped for about 30 minutes. Sample collection and
flow measurements began after the water flow through the
system was constant as determined by uniform flow
meter and pressure readings (1150 gpm and 35 ± 1 psi). For
each sampling event, the unit was operated at a constant
pressure for approximately one hour, during which time
samples were collected at designated sampling points.
4.3 Sampling and Measurement
Locations
Sampling locations were selected based on the
configuration of the irrigation system and demonstration
objectives; analytical parameters were selected based on
the contaminants to be treated and project objectives. The
sampling points for this demonstration are shown in
Figure 1.
The influent sampling location was designated SQ.
Effluent points were labeled S; S12.
Influent Location: Sample point S0 represents
the pivot (influent stream sampling point).
Effluent Locations: Sample points S, S12
represent the effluent from the sprinkler system
(i.e. the sprinkler mist).
Influent VOC water samples were collected at 15-minute
intervals from a faucet at the pivot after constant water
pressure (35 ± 1 psi) was obtained. Process measurements
(air temperature, water temperature, water pressure, flow
rate, pH, and relative humidity) were measured and
recorded before each influent sample was taken. Wind
speed, wind direction, and barometric pressure were
obtained prior to the start of each, and at the end of each
sampling run from the National Oceanic Atmospheric
Administration (NOAA) office in Hastings.
The effluent stream was sampled after constant water
pressure was obtained. One sample at each of the four
heights was taken from each sample location. The sample
scheme was repeated for each of three runs. Samples were
analyzed for critical VOCs.
15
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SO
D
3.2-
2.3-
1.4-
0.5
Sample Height(m)
S2 S3 S4 S5 S6 S7 S8 S9 S10 Sll S12
22 44 66
110 132 154 170 198 220 242 262
262 meters
Figure 1. Sampling point location diagram.
4.3.1 Sampling and Analytical Methods 4.3.1.1 Water Samples
This section describes the procedures for collecting
representative samples at each sampling location and
analyzing collected samples. Water samples were
collected at thirteen locations. These locations include
twelve effluent water sampling locations and one influent
water sampling location, as previously described.
Sampling began after the system was considered to be
operating at constant pressure.
There were twelve collectors installed along the length of
the pivot arm, approximately 3.7 m (12.1 ft) to its north.
This positioning was arranged in order to maximize
collection of the relatively fine droplets of the sprinkler
mist. The collectors were fabricated from stainless steel.
Each collector consists of four rings. Each ring supported
an 11-inch glass funnel that collected the sprinkler mist.
Each funnel support was attached to a hardened steel rod
welded at three-foot intervals to the main vertical support
(see Figure 2).
The sampling device allows water droplets to be collected
at four different heights, 0.5,1.4,2.3, and 3.2 meters (1.6,
4.6, 7.5, and 10.5 ft) above ground, at each of the 12
effluent sampling locations.
A total of 144 primary samples were collected during this
demonstration. In addition, duplicates, blanks, and spare
samples were also collected for quality control (QC)
purposes.
Effluent water samples were collected in new, precleaned
and prelabeled 60-mL Teflon-lined screw cap glass vials
at each of the 12 locations using a stratified water droplet
collector. The sample vial was held beneath the funnel
until filled. Care was taken to completely fill each vial so
that all of the air would be displaced when the vial was
filled with water. If air was present after filling, then
additional sample was added and the vial was recapped.
This procedure was sometimes repeated several times. If
the sampler could not exclude the air after three attempts,
the water was poured out and a new sample was collected
in the same vial. If three attempts did not produce an
acceptable sample, a new vial was filled.
Influent samples were collected by holding the sample vial
under the stream of water at the pivot tap. The same
procedures used for displacing air of the effluent samples
were used for influent samples. Table 5 lists the analytical
procedure used for samples collected during the
demonstration.
6
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3.7m
3.2m
2.3m
1.4m
0.6m.
it/in
,i{*~~ Stalnlaaa StMl Laadar
/IN -
\~ /** Slalnlaaa Sticl Circular Frama
Y^^~~" 'Olaaa Funnal
^ I*"* «o ml VOC Vlil
^- Clamp
^*"~ Fixed Icm SlalnlMi Steal Rod
ft///
^ Hardened Staal Staka
Figure 2. Stratified water droplet collector.
Table 5. Summary Table of Standard Analytical Methods and Procedures
Parameter
VOCs
Sample
Type
Influent
and
Effluent
Method Method Title
Number
551.1 Determination of Chlorination
Disinfection Byproducts,
Chlorinated Solvents, and
Halogenated Pesticides/
Herbicides in Drinking Water by
Liquid-Liquid Extraction and Gas
Chromatography with Electron
Capture Detection
Method Type Source
GC/ECD EPA Methods for the
Determination of Organic
Compounds in Drinking
Water
17
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4.3.2 Quality Assurance and Quality
Control Program
Quality control checks and procedures were an integral
part of the sprinkler irrigation demonstration to ensure that
the QA objectives were met. These checks focused on the
collection of representative samples and the generation of
comparable data. The QC checks and procedures
conducted during the demonstration were: (1) checks
controlling field activities, such as sample collection and
shipping, (2) checks controlling laboratory activities,
such as extraction and analysis, and (3) comparison with
results obtained by EPA Region 7, Including performance
evaluation samples and split field samples (§ 4.4 ). The
results of field and laboratory quality control checks are
summarized in the following sections. Tables 6-22
provide the results of sampling and QA/QC activities.
4.3.2.1 Field Quality Control Checks
As a check on the quality of field activities, including
sample collection, shipment, and handling, three types of
field QC checks, field blanks, trip blanks, and temperature
blanks were employed. In general, these QC checks assess
contamination and temperature of the samples, and ensure
that the degree to which the analytical data represent actual
site conditions is known and documented. The field QC
results are reported in Section 4.3.3 and Tables 19, 20 and
22.
4.3.2.2 Laboratory Quality Control Checks
Laboratory QC checks were designed to determine the
precision and accuracy of the analyses, to demonstrate the
absence of interferences and contamination from
glassware and reagents, and to ensure the comparability of
data. Laboratory-based QC checks consisted of method
blanks, matrix spikes (MS), duplicates, surrogate spikes,
and a comparison with Region 7 performance evaluation
samples. The laboratory also performed initial
calibrations and continuing calibration checks according
to the specified analytical method (see Table 5). The
results of the laboratory internal QC checks for critical
parameters are summarized in Section 4.4.3 and Tables
13-18, and 21.
4.3.2.3 Field and Laboratory Audits
EPA technical systems audits of field and laboratory
activities were conducted July 17 and July 22, 1996.
During these audits, observations and suggestions were
noted in the areas of (1) project organization and
management, (2) field operations and field measurements,
(3) sample log-in and custody, and (4) laboratory
procedures.
4.4 Demonstration Results
This section presents the operating conditions, results and
discussion, data quality, and conclusions of the sprinkler
irrigation SITE demonstration. The results of this
demonstration, combined with previous results obtained
by UNL, provide significant performance data and serves
as the foundation for conclusions about the system's
effectiveness and applicability to similar remediation
projects.
4.4.1 Operating Conditions
During the SITE demonstration, the sprinkler irrigation
system was operated at a pressure of approximately 241
Kpa (35 psi), the limit at which the current system had
previously been tested. The water flow rate at this pressure
was 13 1 ft3/min (1150 gpm). These values were selected
in order to be consistent with the operating conditions
during previous UNL tests. To document the system's
operating conditions, the pressure gauge and flowmeter
readings were recorded at 15 minute intervals. For
demonstration purposes, the system operated for a total of
three hours. The demonstration consisted of three tests,
each for a period of one hour.
Additional parameters that could affect the system
performance, but could not be manually controlled, were
monitored. These include the wind speed and direction,
air temperature, water temperature, and humidity. The
barometric pressure and pH were also recorded, although
the impact of these parameters on system performance are
not considered significant. Appendix B contains all
process measurement data.
Weather conditions during the demonstration were
obtained from a NOAA weather station located at the
Hastings airport, which is approximately 3 km (1.4 miles)
northwest of the demonstration site.
4.4.1.1 Sprinkler System Configuration
The sprinkler system evaluated during this demonstration
was a Valley 8000 center pivot irrigation system equipped
18
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Table 6. Percent Removal for VOCs
Compound
TCE
CT
PCE
TCA
EDB
Table 7. Quality
Critical
Measurements
TCE; CT;
TCA; PCE
EDB
Mass
(551.1)
Mean Influent Mean Effluent
Concentration Concentration
(//g/L) fczg/L)
530 13
4.9 0.18
7.6 0.23
7.2 0.22
1.7 0.076
Standard
Deviation
0.56
0.007
0.011
0.009
0.003
Mean Effluent
Concentration,
Height 1
5.8
0.11
0.13
0.12
0.065
Overall
Percent
Removal
98
96
97
97
96
Height 1
Percent
Removal
99
98
98
98
96
Assurance Objectives for Critical Project Measurements
Matrix Method Units
Water 551.1 [igll
(Extraction with
methyl-t-but-$
ether ( MTBE))
Water
N/A Balance Check g
with 2 Standard
Weights (50g&
100g)
MDL
0.1
M9/L
0.02
M9/L
N/A
Precision 1
RPD
Influent ± 20%
Effluent ± 30% or
±0.1pg/L3
Influent ± 20%
Effluent ± 30%
or ±0.01 fj.g/13
N/A
Accuracy 2
%R
80-120%
80-I 20%
±0.1g
Completeness
100%
100%
100%
Notes:
'Precision was evaluated from field duplicate results.
2Accuracy was evaluated from matrix spike (MS) results.
3Whichever was greater for effluent samples.
19
-------
Table 8. Hastings Sprinkler Irrigation Demonstration Results - Influent
Sample ID
and Data
Package
Number
MINF1(9)
MINF2 (9)
MINF3 (9)
MINF4(9)
NINF1 (9)
NINF2 (9)
NINF3 (9)
NINF4 (9)
EINF1 (11,14)
EINF2(11,14)
EINF3(11,14)
EINF4(11,14)
TCA (ppb)
8.1
7.4
7.3
a
6.8
7.1
7.0
7.1
7.1
6.9
7.1
7.2
CT (ppb)
5.6
5.0
4.9
a
4.7
4.8
4.8
4.9
4.8
4.7
4.9
4.9
TCE (ppb)
559
538
484
482
535
563
537
541
555
507
533
526
EDB (ppb)
1.9
1.8
1.8
a
1.5
1.6
1.6
1.6
1.6
1.6
1.6
1.6
PCE (ppb)
7.8
7.4
7.6
a
7.4
7.8
7.6
7.9
7.6
7.4
7.6
7.5
Surrogate
Recovery%
108
104
107
ND
103
108
105
106
106
103
103
102
Notes:
a There was a problem with the MINF4 injection for compounds with a low concentration. It is believed
that the autosample syringe did not inject any sample, therefore, no data were generated for TCA, CT,
EDB, and PCE. (TCE was analyzed separately due to its higher concentration). Surrogate recovery also
could not be determined.
ND - Not determined.
20
-------
Table 9. Hastings Sprinkler Irrigation Demonstration Results - Height 1
Sample ID
and Data Package
Number
M-SI-HI (15)
M-S6-H1(1)
N-S2-H1 (3)
N-S5-H1(15)
N-S6-H1 (3)
N-S9-H1 (15)
N-S1 1-H1 (4)
E-S1-H1(5)
E-S2-H1 (5)
E-S3-H1 (5)
E-S4-H1 (5)
E-S5-H1 (5)
E-S6-H1 (6)
E-S7-H1 (6)
E-S8-H1 (7)
E-S9-H1 (6)
E-SIO-HI (8)
E-S11-H1(6)
E-S12-H1 (7)
TCA (ppb)
0.14
0.12
0.097
0.14
0.092
0.12
0.055 D
0.083 D
0.13 D
0.091 D
0.032 D
0.10D
0.099
0.091
0.13
0.15
0.11
0.088
0.29
CT(ppb)
0.12
0.078
0.084
0.12
0.088
0.10
0.043
0.075
0.10
0.078
0.032
0.096
0.095
0.082
0.10
0.14
0.10
0.075
0.29
TCE (ppb)
8.5
5.2
4.9
6.8
5.3
5.5
>15H
4.3
6.5
4.4
4.1
5.9
5.8
5.0
5.3
9.1
6.2
4.3
8.5
EDB (ppb)
0.054
0.026 L
0.042
0.055
0.047
0.046
0.029 L
0.043
0.053
0.643
0.046
0.051
0.048
0.051
0.064
0.069
0.056
0.041
0.22»
PCE (ppb)
0.14
0.11
0.11
0.14
0.11
0.12
0.068
0.094
0.13
0.095
0.10
0.12
0.12 D
0.10 D
0.12
0.16 D
0.12 D
0.10 D
0.28
Surrogate
Recovery
%
116
126
92
126
104
122
112
111
97
105
88
104
102
110
109
I II
106
116
102
Notes:
8 Duplicate sample showed 0.068 ppb
D The CCV closest to sample concentration (diluted sample concentration if applicable) was outside 70%-130%
range. (Effluent samples: 0.5 ppb for TCA, CT, EDB, PCE; 5.0 ppb for TCE)
(Influent samples: 5.0 ppb for TCA, CT, EDB, PCE, and TCE)
H Value was estimated because it was outside of the calibration range and could not be reanalyzed.
L Value was estimated because it was less than the low standard, but greater than the MDL.
21
-------
Table 10. Hastings Sprinkler Irrigation Demonstration Results - Height 2
Sample ID
and Data Package
Number
M-SI-H2 (1)
M-S6-H2(15)
N-S5-H2 (3)
N-S6-H2 (3)
N-S7-H2 (3)
N-S12-H2(15)
E-S2-H2 (5)
E-S5-H2 (5)
E-S8-H2 (6)
E-S9-H2 (6,7)
E-S10-H2(15)
E-S11-H2(6)
E-S12-H2 (15,16)
TCA (ppb)
0.20
0.13
0.14
0.13
0.095
0.19
0.18 D
0.24 D
0.17
0.27
0.13
0.18
0.27
CT(ppb)
0.15
0.11
0.13
0.12
0.081
0.17
0.15
0.18
0.14
0.23
0.12
0.15
0.24
TCE (ppb)
9.8
6.3
8.4
7.2
4.9
10
10
13
9.4
18
6.9
9.7
17
EDB (ppb)
0.046
0.051
0.060
0.051
0.042
0.074
0.067
0.087
0.089
0.092
0.053
0.072
0.11
PCE (ppb)
0.19
0.13
0.15
0.14
0.11
0.20
0.18
0.22
0.17 D
0.29 D
0.14
0.18 D
0.29
Surrogate
Recovery
%
125
125
105
105
106
122
113
117
111
111
122
122
117
Notes:
D The CCV closest to sample concentration (diluted sample concentration if applicable) was outside 70%-130%
range. (Effluent samples: 0.5 ppb for TCA, CT, EDB, PCE; 5.0 ppb for TCE)
(Influent samples: 5.0 ppb for TCA, CT, EDB, PCE, and TCE)
H Value was estimated because it was outside of the calibration range and could not be reanalyzed.
L Value was estimated because it was less than the low standard, but greater than the MDL.
22
-------
Table 11. Hastings Sprinkler Irrigation Demonstration Results - Height 3
Sample ID
and Data Package
Number
M-S4-H3(1)
M-S6-H3(1)
M-S7-H3(1)
N-S2-H3 (3)
N-S6-H3(15)
N-S10-H3(4)
E-S4-H3(15)
E-S5-H3 (5)
E-S8-H3 (6,7)
TCA (ppb)
0.26
0.28
0.27
0.25
0.20
0.23 D
0.21
0.27 D
0.31
CT(ppb)
0.19
0.20
0.19
0.22
0.17
0.19
0.17
0.23
0.26
TCE (ppb)
>15H
>15H
>15H
16
10
14
11
21
21
EDB (ppb)
0.065
0.058
0.063
0.081
0.062
0.080
0.069
0.094
0.11
PCE (ppb)
0.26
0.29
0.26
0.26
0.19
0.23
0.21
0.28
0.33 D
Surrogate
Recovery
%
127
124
112
110
125
104
119
109
114
Notes:
D The CCV closest to sample concentration (diluted sample concentration if applicable) was outside 70%-130%
range. (Effluent samples: 0.5 ppb for TCA, CT, EDB, PCE; 5.0 ppb for TCE)
(Influent samples: 5.0 ppb for TCA, CT, EDB, PCE, and TCE)
H Value was estimated because it was outside of the calibration range and could not be reanalyzed because it
was less than the low standard, but greater than the MOL.
23
-------
Table 12. Hastings Sprinkler Irigation Demonstration Results - Height 4
Sample ID
and Data Package
Number
M-S1-H4(1)
M-S2-H4(15)
M-S4-H4(15,16)
M-S5-H4(1)
N-SI-H4 (3)
N-S11-H4(4)
N-S12-H4 (4,5)
E-S3-H4 (5)
E-S5-H4 (6)
E-S11-H4(6,7)
TCA(ppb)
0.28
0.31
0.33
0.67
0.23
0.33 D
0.43 D
0.35 D
0.34
0.44
CT(ppb)
0.21
0.26
0.28
0.47
0.19
0.28
0.34
0.29
0.29
0.38
TCE (ppb)
>15H
>15H
19
>15H
14
25
29
21
23
30
EDB (ppb)
0.057
0.089
0.11
0.16
0.074
0.11
0.14
0.12
0.11
0.14
PCE (ppb)
0.27
0.31
0.32
0.75
0.23
0.34
0.44
0.35
0.37 D
0.48 D
Surrogate
Recovery
%
127
126
118
121
102
105
107
110
106
108
Notes:
D The CCV closest to sample concentration (diluted sample concentration if applicable) was outside 70%-130%
range.
(Effluent samples: 0.5 ppb for TCA, CT, EDB, PCE; 5.0 ppb for TCE)
(Influent samples: 5.0 ppb for TCA, CT, EDB, PCE, and TCE)
H Value was estimated because it was outside of the calibration range and could not be reanalyzed..
L Value was estimated because it was less than the low standard, but greater than the MOL.
24
-------
Table 13. QC Results for Groundwater Analyses - Duplicates (TCA)
Sample
Name
MS1 H2
MS1 H4
MS5H3
MS6H1
NS6H1
NS7H2
NSI OH3
NS10H4
ES3H4
ES5H3
ES8H2
ES12H1
MINF4"
NINF4
EINF4
Odl 1 I|JIC
Concentration
0.21
0.28
0.31
0.12
0.092
0.095
0.23 D
0.50 D
0.35 D
0.27 D
0.17
0.29
7.1
7.2
uupiiucue
Concentration
//g/L
0.18
0.27
0.37
0.12
0.091
0.12 D
0.19 D
0.41 D
0.33 D
0.29
0.13
0.12
7.0
7.7
RPD
15
3.6
18
0.0
1.1
23
19
20
5.9
7.1
27
83*
1.4
6.7
aThere was a problem with the MINF4 injection for compounds
with a low ppb concentration. It is believed that the autosample syringe
did not inject any sample, therefore, no data were generated for TCA,
CT, EDB, and PCE. (TCE was analyzed separately due to its higher
concentration). Surrogate recovery also could not be determined.
* Outside of control limit.
D The CCV closest to sample concentration (diluted sample
concentration if applicable) was outside 70%-1 30% range.
(Effluent samples: 0.5 ppb for TCA, CT, EDB, PCE; 5.0 ppb for TCE)
(Influent samples: 5.0 ppb for TCA, CT, EDB, PCE, and TCE)
25
-------
Table 14. QC Results for Groundwater Analyses - Duplicates (CT)
Sample
Name
MS1 H2
MS1H4
MS5H3
MS6H1
NS6H1
NS7H2
NS10H3
NS10H4
ES3H4
ES5H3
ES8H2
ES12H1
MINF4a
NINF4
EINF4
Sample
Concentration
M9/L
0.15
0.21
0.22
0.078
0.088
0.081
0.19
0.38
0.29
0.23
0.14
0.29
4.9
4.9
Duplicate
Concentration
A*g/L
0.14
0.21
0.27
0.081
0.085
0.10
0.17
0.35
0.27
0.25
0.11
0.11
4.8
5.3
RPD
6.9
0.0
20
3.8
3.5
21
11
8.2
7.1
8.3
24
90*
2.1
Notes:
a There was a problem with the MINF4 injection for compounds with a low
ppb concentration. It is believed that the autosample syringe did not inject
any sample, therefore, no data were generated for TCA, CT, EDB, and PCE.
(TCE was analyzed separately due to its higher concentration). Surrogate
recovery also could not be determined.
* Outside of control limit.
26
-------
Table 15. QC Results for Groundwater Analyses - Duplicates (TCE)
Sample
Name
MS1 H2
MS1 H4
MS5H3
MS6H1
NS6H1
NS7H2
NS10H3
NS10H4
ES3H4
ES5H3
ES8H2
ES12H1
MINF4
NINF4
EINF4
Sample
Concentration
/zg/L
9.8
17H
20 H
5.2 H
5.3
4.9
14
26
21
21
9.4
8.5
482
541
526
Duplicate
Concentration
M9/L
9.1
17H
25 H
5.5
5.1
6.2
12
32
21
20
7.2
5.8
530
540
583
RPD
7.4
0.0
22
5.6
3.8
23
15
21
0.0
4.9
27
38*
9.5
0.2
10
Notes:
* Outside of control limit.
H Value was estimated because it was outside of the
calibration range and could not be reanalyzed.
27
-------
Table 16. QC Results for Groundwater Analyses - Duplicates (EDB)
Sample
Name
MS1 H2
MS1H4
MS5H3
MS6H1
NS6H1
NS7H2
NS10H3
NS10H4
ES3H4
ES5H3
ES8H2
ES12H1
MINF4a
NINF4
EINF4
Sample
Concentration
Mg/L
0.046
0.057
0.075
0.026 L
0.047
0.042
0.080
0.18
0.12
0.094
0.069
0.22
1.6
1.6
Duplicate
Concentration
M9/L
0.040
0.059
0.086
0.028 L
0.043
0.047
0.071
0.14
0.11
0.092
0.055
0.068
1.6
1.7
RPD
14
3.4
14
7.4
8.9
11
12
25
8.7
2.2
23
106*
0.0
6.1
Notes:
a There was a problem with the MINF4 injection for compounds
with a low ppb concentration. It is believed that the autosample
syringe did not inject any sample, therefore, no data were
generated for TCA, CT, EDB, and PCE. (TCE was analyzed
separately due to its higher concentration). Surrogate recovery
also could not be determined.
* Outside of control limit.
L Value was estimated because it was less than the low
standard, but greater than the MDL.
28
-------
Table 17. QC Results for Groundwater Analyses - Duplicates (PCE)
Sample
Name
MS1 H2
MS1 H4
MS5H3
MS6H1
NS6H1
NS7H2
NS10H3
NS10H4
ES3H4
ES5H3
ES8H2
ES12H1
MINF48
NINF4
EINF4
Sample
Concentration
A*g/L
0.19
0.27
0.33
0.11
0.11
0.11
0.23
0.64
0.35
0.28
0.17 D
0.28
7.9
7.5
Duplicate
Concentration
M9/L
0.18
0.27
0.39
0.11
0.11
0.13
0.20
0.43
0.33
0.30 D
0.14 D
0.13
7.6
8.2
RPD
5.4
0.0
17
0.0
0.0
17
14
39*
5.9
6.9
19
73*
3.9
8.9
Notes:
a There was a problem with the MINF4 injection for compounds
with a low ppb concentration. It is believed that the autosample
syringe did not inject any sample, therefore, no data were
generated for TCA, CT, EDB, and PCE. (TCE was analyzed
separately due to its higher concentration). Surrogate recovery
also could not be determined.
* Outside of control limit.
D The CCV closest to sample concentration (diluted sample
concentration if applicable) was outside 70%-1 30% range.
(Effluent samples: 0.5 ppb for TCA, CT, EDB, PCE; 5.0 ppb for TCE)
(Influent samples: 5.0 ppb for TCA, CT, EDB, PCE, and TCE)
29
-------
Table 18. QC Results for Groundwater Analyses
Sample Number
(Spike Concentration, ppb)
MS or MSD
[Data Sets]
Matrix Spike Recovery (%)
TCA
CT
TCE
EDB
PCE
M-S5-H4 (5.0) MSD [1/15,16]
M-S1 I-H3 (0.5) MSD [2/8]
M-SIP-HI (5.0) MS [2/15]
M-S12-H2 (5.0) MS [2/8]
N-S2-H3 (0.5) MS [3/4]
N-S2-H3(1 .0) MSD [3/8]
N-S5-H2 (5.0) MS [3/4]
N-S1 I-HI (0.5) MS [4/8]
N-S1 2-H4 (0.5) MS [4,5/8]
E-S7-H1 (5.0) MS [6/8]
E-S8-H3 (0.5) MS [6,7/8]
E-S9-H2 (0.5) MS [6,7/8]
E-S1 I-H4 (0.5) MS [6,7/8]
MINF4(5.0)MS[9/11,14]b
NINF4 (5.0) MS [9/11,141
EINF4(5.0) MS [11, 14/1 1,14]
QA Recovery Objective
121
100
112
95
130
125
99
117
104
100
114
114
96
98
78
80-120
125
94
115
96
88
108
97
103
90
102
96
96
80
-
94
100
80-120
115
106
104 105
118 103
98
122
112 99
104
104
98 101
106
106
102
*
100
93
80-I 20 80-120
113
86
108
93
106
114
97
96
106
98
106
108
88
82
95
80-120
Notes:
* Inappropriate spike level: spike amount too low compared to sample concentration.
* While a 5.0 ppb spike was used, the native concentration of TCE in this effluent sample was seven times greater
(i.e., 35 ppb). Recovery was 60%.
B There was a problem with the MINF4 injection for compounds with a low ppb concentration. It is believed that the
autosample syringe did not inject any sample, therefore, no data were generated for TCA, CT, EDB, and PCE. (TCE
was analyzed separately due to its higher concentration). Surrogate recovery also could not be determined.
30
-------
Table 19. QC Results of Field Blank Analyses
Blank Type
(Data Set)
Field (1)
Field (3)
Field (4)
Acceptance
Criteria
MDL
TCA
M9/L
.029 u
.027 U
.051
<40
0.036
CT
^g/L
.0084 U
.0083 u
.012 u
<1
0.030
TCE
//g/L
.01 6 U
.017 u
.022 u
<1
0.025
EDB
^g/L
ND
ND
ND
<0.018
0.018
PCE
M9/L
.013 u
.038
.038
<1
0.036
Notes:
ND Not detected.
U Value was less than the MDL.
Table 20. QC Results of Trip Blank Analyses
Blank Type
(Data Set)
Trip (1)
Trip (3)
Trip (4)
Trip (7)
Trip (9)
Trip (9)
Acceptance
Criteria
MDL
TCA
M9/L
.028 U
.026 U
.026 U
.030 u
.026 U
.042.
c MDL
0.036
CT
wn-
.0077 u
.010 u
,011 u
.020 u
.013 u
.022 u
-------
Table 21. QC Results of Laboratory Blank Analyses
Blank Type
(Data Set)
Laboratory
(2)
Laboratory
(3)
Laboratory
(4)
Laboratory
(5)
Laboratory
(6)
Laboratory
(7)
Laboratory
(8)
Laboratory
(9)
Laboratory
(9)
Laboratory
(11)
Acceptance
Criteria
MDL
TCA^g/L
0.029 u
0.025 U
0.026 U
0.029 u
0.025 U
0.026 U
0.032 U
0.027 U
0.043
0.025 U
<40
0.036
cn>g/L
0.0092 u
0.010 u
0.010 u
0.010 u
0.098
0.013 u
0.0092 u
0.016 U
0.027 U
0.013 u
<1
0.030
TCE M9/L
ND
ND
ND
ND
ND
0.0063 U
0.0062 U
ND
ND
ND
<1
0.025
EDB Mg/L
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
<0.018
0.018
PCE Mg/L
0.0091 u
0.030 u
0.035 u
0.034 u
0.030 u
0.034 u
0.0021 u
0.042
0.013 u
0.041
<1
0.036
Notes:
ND Not detected.
U Value was less than the MDL.
32
-------
Table 22. Temperature Blanks
Cooler Temperature Blank 1, °C
Number
1
2
3
4
5
6
7
8
9
13.5
10.0
10.5
11.5
4.0
2.0
14.0
8.5
2.0*
Temperature Blank 2, °C
13.5
10.0
10.5
12.0
4.0
a
12.5
___a
a
Notes:
* \A/otar tamnaroti ira inoiHa r\f tha /r\r\lar
a Sample was not collected.
with off-the-shelf impact pads. The nozzle aperture along
the pivot arm ranged from 2.0 mm (0.08 in) to 6.4 mm
(0.25 in). The total length of the pivot arm was 232 m
(859ft).
4.4.2 Results and Discussion
This section presents the results of the sprinkler irrigation
SITE demonstration in Hastings, Nebraska and a
comparison of results obtained from split sample which
were collected by Region 7 personnel. The results are
presented by, and have been interpreted in relation to,
project objectives. The data used to evaluate the primary
objective are presented in Tables 8-12. Data quality and
conclusions based on these results are presented in Section
4.4.3. A discussion of the sampling activities and results
obtained by Region 7 is provided in Appendix C.
The data obtained from the experiment were analyzed to
statistically determine if the average concentration of
VOCs exceeds the stated MCLs. All statistical inference
and estimation were based on the fact that samples were
collected using stratified random sampling (Appendix D).
4.4.2.1 Primary Objective
The primary objective was considered critical for the
evaluation of the sprinkler irrigation system as a
remediation and disposal alternative for VOC contaminated
groundwater.
Primary Objective
Determine the efficacy of the sprinkler irrigation system to
treat groundwater contaminated with VOCs to
concentrations that average below the MCLs; specifically,
TCE (<5/jg/L), CT(<5 ug/L), PCE (<5 ug/L), TCA (<200
), and EDB (<0.05 /jg/L) at a 95% confidence level.
This objective was achieved by collecting samples of the
sprayed effluent water which was emitted from the nozzles
along the arm of the system and analyzing the samples for
VOCs.
Based on the results of data from all sampling heights, the
mean effluent concentration of TCA (0.224 ug/L), CT
(0.183 ug/L), and PCE (0.23 1 ug/L) were shown to be well
33
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below the respective MCLs of 200 ug/L (p=l .0000), 5 ug/
L (p=l .0000), and 5 ug/L (p= 1.0000). A 95% confidence
interval on the mean level of TCA was (0.206,0.242),
(0.169,0.196) for CT, and (0.210,0.252) for PCE. For
TCE, the mean concentration (12.623) was shown to be
significantly greater than theMCL of 5 ug/L (p=.0001). A
95% confidence interval on the mean level was (11.52,
13.72). The mean concentration of EDB (0.076) was
shown to be significantly larger than the MCL of 0.05 ug/
L (p=0.0001). A 95% confidence interval on the mean
level was (0.069,0.082). Table 6 presents the mean
influent concentration for all contaminants of concern.
The results of data from the lowest sample collection
height indicate that the mean effluent concentration of
TCA (0.116 ug/L), CT (0.108 ug/L), and PCE (0.128 ug/
L) were well below the respective MCLs. A 95%
confidence interval on the mean level of TCA was
(0.087,0.145), (0.079,0.136) for CT, and (0.104,0.152) for
PCE. For TCE, the mean concentration (5.783) ug/L was
shown to be significantly greater than the MCL. A 95%
confidence interval on the mean level was (5.022,6.545).
The data collected provided no indication that the mean
level of EDB (0.065) was significantly larger than the
MCL. A 95% confidence interval on the mean level was
(0.042,0.089) which overlaps the 0.05 ug/L MCL for
EDB.
A summary of the data analysis is provided hi Appendix E.
4.4.2.2 Secondary Objectives
Secondary objectives provide additional information that
is useful, but not critical, for the evaluation of the sprinkler
irrigation technology. Four secondary objectives were
selected for the SITE demonstration of the sprinkler
irrigation system. The noncritical measurement
parameters required to achieve the secondary project
objectives are presented in Table 3.
4.4.2.2.1 Secondary Objective S-l
Determine costs associated with the application of the
technology.
The estimated cost to install a sprinkler irrigation system
and perform compliance sampling at the Hastings site
ranges from $58K to $97K (see Table 2). Operation and
maintenance costs are estimated to be $35K per year.
Labor and utility (pumping) costs will vary depending on
the site location and crop and are estimated to be 0.05-0.1
man-hr/acre-inch and 1.00-1.75 $/acre-inch, respectively.
4.4.2.2.2 Secondary Objective S-2
Evaluate air emissions risks using the ISCST3.
Removal of the VOCs from groundwater and subsequent
release into the atmosphere in the gaseous phase could
pose a potential inhalation risk to individuals working or
residing in the area of the irrigation system. The NDOH
evaluated the magnitude of this inhalation risk and
determined the carcinogenic risk and hazard index
(Appendix F).
The risk assessment evaluated inhalation risks for the most
likely individuals to be exposed to the irrigation system,
specifically, site workers and observers present during the
demonstration and nearby residents exposed to emitted
volatiles during a long-term remediation at the site. The
locations of these receptors in relation to the irrigation
system were identified using a global positioning system.
The average concentrations of contaminants detected in
the groundwater were input into the Industrial Source
Complex Model (ISCST3) to predict volatile concentrations
of these chemicals from the irrigation system. The
concentrations of contaminants in the air as well as the
standard default assumptions were utilized to quantify the
noncarcinogenic and carcinogenic risks potentially
associated with the SITE Demonstration.
The proposed remediation technology is predicted to
operate 24 hours/day during a maximum summer
irrigation season in Nebraska of 90 days. The potential
inhalation risk for two of the nearest residents to the
irrigation system was evaluated by the NDOH. The
noncarcinogenic and carcinogenic risks for a child
resident at both of these locations was quantified to ensure
protection of this sensitive subgroup.
The carcinogenic risks were calculated to be: TCE - 2.41 x
lO'10; CT - 1.45 x 10'10; and EDB - 7.8 x 10-". The
calculated hazard indexes were: TCA - 9.48 x 10'8; CT -
3.40 x 10'5; and EDB -1.32 x lO'4. The Carcinogenic Risk
Reference Value was 1 x 10-6. The Hazard Index
Reference Value was 1.00.
Predicted carcinogenic risk factors and hazard risks were
also calculated for remediation applications.
34
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For remediation applications, the technology is predicted
to operate 24 hours/day during a maximum summer
irrigation in Nebraska of 90 days. The potential inhalation
risk for two of the nearest residents to the irrigation system
was evaluated by the NDOH. The noncarcinogenic and
carcinogenic risks for a child resident at both of these
locations was quantified to ensure protection of this
sensitive subgroup.
The carcinogenic risks were calculated to be: TCE -1.83 x
10-10; CT - 0.92 x 10'9; and EDB - 0.74 x lO'10. The
calculated hazard indexes were: TCA -1.75 x 10'7; CT -
2.13xlO'3;and EDB-1.18x lO'4. The Carcinogenic Risk
Reference Value was 1 x 10-6. The Hazard Index
Reference Value was 1.00.
4.4.2.2.3 Secondary Objective S-3
Calculate the average percent removal of critical VOCs in
the sprinkler mist.
Based on the sprinkler irrigation demonstration results, the
overall reduction of individual VOCs were: TCE - 98%,
CT - 96%, PCE - 97%, TCA - 97%, and EDB - 96%. The
overall percent removal for each VOC is shown in Table 6.
4.4.2.2.4 Secondary Objective S-4
Calculate the average percent removal of critical VOCs at
the lowest sampling height during the last sampling run.
All samples collected during the last sampling run from
the lowest sampling height (H,) were analyzed in order to
determine an average percent removal of critical VOCs.
The results of data from the lowest sample collection
height indicate that the average percent removals were:
TCE - 99%, CT - 98%, PCE - 98%, TCA - 98%, and EDB
- 96%. The overall percent removal for each VOC is
shown in Table 6.
4.4.3 Data Quality
This section discusses the QA data with respect to project
QAobjectives. Specifically, instances of nonconformance
and the impact, if any, on the overall project objectives are
discussed. Tables 13-22 summarize key QA/QC data with
respect to the QA objectives, field QA/QC, and internal
QC.
A data quality assessment was conducted to incorporate
the analytical data validation results and the field data
quality QC results, evaluate the impact of all QC measures
on the overall data quality, and remove all values which
did not meet QC criteria from the investigation data set.
The results of this assessment were used to produce the
known, defensible information used to define the
evaluation findings and derive conclusions.
The overall QA objective for the SITE Program
demonstration was to produce well-documented data of
known quality as indicated by the data's precision and
accuracy, completeness, representativeness, comparability,
and the reporting limits for the analytical methods.
Specific quality assurance objectives were established as
benchmarks by which each of these criteria would be
evaluated. The following sections outline the QA
objectives that were established.
4.4.3.1 Critical Parameters
This subsection discusses conformance with QA
objectives for laboratory analyses for all critical
parameters analyzed by EPA NRMRL. QA objectives for
laboratory analysis of critical VOCs (TCA, CT, TCE,
EDB, PCE) were evaluated based on MSs, blanks,
duplicates, surrogate compound analysis, and calibration
criteria. QA objectives for the critical mass measurements
made in the laboratory were evaluated based on
measurement of a standard weight.
4.4.3.1.1 Completeness
The QA Objective for data completeness specified by the
QAPP stipulated that 100 percent of all effluent sample
measurements necessary to draw statistically valid
conclusions would be obtained and would be valid. A May
22,1996 memorandum estimating sample size states "the
recommended number of total samples 40. The 40
samples would be evenly distributed across each strata, ten
samples from each sampling height. The samples would
be randomly selected from the 36 samples collected at
each height."
Due to significant analytical variations, (i.e., continuing
calibration checks and surrogates fell outside acceptance
criteria) sample results generated from 07/22/96 to 07/23/
96 were not used to draw conclusions. The GC was
recalibrated and back-up samples were analyzed to obtain
data for 10 samples from each strata, with one exception.
35
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Adequate quality data were generated for only nine height
3 samples. Thus, the percent completeness was actually
97.5% instead of 100%. All sample results used to
evaluate objectives are reported. These results are
discussed in more detail in Appendix E. All effluent
samples were analyzed within the holding times specified
in the QAPP.
The statistical analysis performed weighted each strata
based on the number of samples present. Therefore,
although only 97.5% completeness was achieved, a
sufficient number of valid VOC measurements were
obtained to evaluate the project objectives.
4.4.3.1.2 Comparability and Analytical
Reporting Limits
All critical VOC data are considered to be comparable. As
specified by the QAPP, the EPA NRMRL laboratory used
Method 551.1 (USEPA, Revision 1.0) to analyze all VOC
sample fractions. The low-level method detection limits
(MDL) specified in Table 7 were mostly met in the MDL
study performed prior to the project. The MDLs for TCA,
CT, TCE, EDB, and PCE were 0.036 ng/L, 0.030 ug/L,
0.025 ug/L, 0.018 ug/L, and 0.036 ug/L, respectively.
4.4.3.1.3 Accuracy and Precision
QA Objectives for accuracy and precision were evaluated
based on MS percent recoveries and relative percent
differences (RPDs) respectively. Surrogate compound
percent recovery values also supported QA Objectives for
accuracy.
ACCURACY - Matrix Spikes
As specified in the QAPP, field personnel collected three
sequential samples to provide a primary sample, an MS
sample, and a back-up matrix spike duplicate (MSD)
sample (i.e., the MSD sample was only used if the MS
sample was unusable). Sixteen primary/MS/MSD
effluent sample triplicates were collected. In addition,
three primary MS/MSD influent sample triplicates were
collected. Table 18 details MS recovery results for 13
spiked samples (i.e., data generated from 07/22/96-07/23/
96 are not reported). Seven of the thirteen effluent MS or
MSD samples were spiked at 0.5 ppb, five were spiked at
5.0 ppb, and one was spiked at 1.0 ppb. The samples were
spiked at different concentrations to obtain recovery
results for all five critical contaminants. Typically, the 0.5
ppb and 1.0 ppb spikes were appropriate for TCA, CT,
EDB, and PCE in the effluent samples. The 5.0 ppb spike
was appropriate for TCE in the effluent samples and for
TCA, CT, EDB, and PCE in the influent samples. The
influent TCE concentration was too high to enable an
adequate spike to be performed.
All critical spike data exhibited recoveries within 70-
130% (when spiked at the appropriate level).
The following was observed:
All TCA, CT, EDB, and PCE data exhibited
recoveries within the QAPP specified limits (80-
120%) except four TCA recoveries, one CT
recovery, and one EDB recovery. As previously
stated, these results were within 70-130%.
All appropriately spiked samples for TCE
exhibited recoveries within the QAPP specified
limits (80-120%).
Because the MCL for TCA was 200 ppb, and sample
results for TCA were all < 1 ppb, the wider recovery results
(70-130%) are acceptable for meeting project objectives
relative to TCA.
Similarly, because sample results for CT were all < 1 ppb,
and the CT MCL was 5 ppb, the wider recovery results (70-
130%) are acceptable for meeting project objectives
relative to CT.
The spike result that was outside QAPP specified limits for
EDB was sample N-S2-H3-MSD. The percent recovery
was 122%. Eleven of the other 12 effluent spike
recoveries were between 98 and 106%. (The remaining
one was 115%). There does not appear to be any matrix
affect with EDB since acceptance criteria was only
slightly exceeded for one spiked sample.
ACCURACY - Surrogates
The acceptance criteria for all samples was 80-120%. The
surrogate recovery for each sample is provided in Tables
8-12. After several samples were analyzed, the analyst
observed that the 80-120% criteria was not met in all cases.
Project and QA Management reviewed the data and
determined that wider acceptance criteria would still allow
project objectives to be met. Therefore, 70-130% was
used. It should be noted that most of the surrogates
36
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exceeded this range in samples analyzed on 07/22/96 and
07/23/96, and therefore, additional samples were
analyzed.
For results used to evaluate project objectives, surrogate
recoveries ranged from 86-127%. Fourteen of the 51
effluent samples had surrogate recoveries between 120-
127%. Because the effluent sample results were
significantly lower than the MCLs for TCA, CT, and PCE,
these higher recoveries have no effect on project
conclusions. In other words, even if sample results were
biased high, TCA, CT, and PCE still met the MCLs.
For TCE and EDB, effluent sample results (total across
heights) were significantly higher than the MCLs for these
compounds. For TCE, even if samples were biased high
by 30%, project conclusions would remain unchanged.
The higher surrogate recoveries have no effect on project
conclusions for TCE. The mean for EDB, however, was
0.076 ppb (EDB MCL was 0.05). If sample results were
biased high (even by < 30%), project conclusions for EDB
may change because the mean is so close to the MCL.
All surrogate recoveries met QAPP specified limits (80-
120%) for Height 1 data; therefore, secondary objective 4
was met.
In sum, it appears that surrogate recoveries obtained for
project samples were acceptable for meeting the primary
project objective with the possible exception of EDB. The
recoveries obtained were acceptable for meeting
secondary objective 4.
ACCURACY - Mass
The determination of mass was made using a standard
analytical balance. The balance calibration was checked
with standard 50 and 100 g weights prior to each use.
PRECISION - Sample Duplicates
As specified in the QAPP, twelve effluent sample
duplicates were collected and analyzed. The results of
these duplicates (see Tables 13-17) indicate that all
compounds met the QAPP specified criteria in all samples
with the exception of PCE in the sample pair N-S10-H4/
N-S10-H4-D, and all compounds in sample pair E-S 12-
H1/E-S12-H1-D.
It should be noted that for sample N-S10-H4, surrogate
recovery was also high (152%). This sample was not
reanalyzed. Because PCE concentrations were well below
the MCL, the higher RPD obtained for the duplicate pair
will not affect project conclusions.
It is uncertain why sample pair E-S 12-H1/E-S12-H1D did
not meet the criteria. No explanation could be derived.
4.4.3.1.4 Represen tativeness and
Sample Contamination
Field personnel ensured representative sampling by
allowing the water to purge through the sprinkler for a
consistent amount of time prior to sampling, and by
collecting samples in the same manner at all similar points.
The EPA NRMRL laboratory analyzed field, trip, and
method (laboratory) blank samples to determine if any
VOCs were potentially introduced during sample
collection, shipping, preparation, and analysis.
Two field blanks for each sampling event were collected to
provide a check on sample contamination originating from
field conditions. Two beakers were filled with distilled
water and were placed upwind of the sprinkler system at
opposite ends of the sprinkler arm at the start of each
sampling run. At the end of the run, the water was poured
into screw cap vials and shipped as samples. One field
blank from each run was analyzed.
Two temperature blanks for each sampling event were
prepared and placed in different locations within the
cooler. These were prepared by filling two extra vials at
the last sampling point (S,2) for each sampling event. The
temperature was measured and recorded when the samples
were received at the laboratory.
Trip blanks are designed to provide a check on sample
contamination originating from sample transport, shipping
and site conditions. Trip blanks for the water sampling
were prepared by filling screw cap glass vials with reagent
water, transferring them to the demonstration site, and
then returning them unopened with the samples to the
laboratory. Two trip blanks were used per cooler.
All field and method blank sample results met QAPP
specified criteria as can be seen in Tables 19 and 21. Three
trip blanks (Table 20) did not meet QAPP specified criteria
for PCE. One of those three did not meet QAPP specified
criteria for TCA. All blank values were still < 0.05 ug/L.
Because sample results were lower than the MCLs for PCE
and TCA, there is no effect on project conclusions due to
37
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these > MDL blank values. The reported concentrations of
critical parameter VOCs appear to be representative of
actual concentrations in the effluent samples based on
available QC data.
The EPA NRMRL laboratory measured the temperature of
the temperature blanks after opening each cooler at the
laboratory. The temperature blank results are indicated in
Table 22.
The results indicate that all samples were not cooled to 4°C
as specified in the QAPP. Because VOC contaminants
could be lost at higher temperatures, sample results could
be biased low. Coolers 3 and 4, however, contained
Region 7 PE samples shipped from the field. The results
of the PE samples were acceptable, therefore it is believed
that sample concentrations were not affected by slightly >
4°C temperatures.
4.4.3.1.5 Conformance with
Calibration Requirements
GC calibration was performed taking into account the
anticipated high levels of TCE compared to all other
contaminants of interest. Two calibration curves were
prepared, a high curve (0.5 ppb to 15 ppb) and a low curve
(0.03 ppb to 1 ppb). A linear fit was used for the low curve,
while a quadratic fit was used for the high curve. Samples
were extracted as specified in the QAPP. One portion of
the extract was saved and the other portion was analyzed.
Contaminant concentrations <1 ppb were quantitated
using the low curve. Contaminant concentrations between
1 ppb and 15 ppb were quantitated using the high curve. In
most cases, if any contaminant concentration exceeded the
range of the high curve (i.e., 15 ppb), the saved extract was
diluted and the diluted extract was injected to obtain the
actual concentration. It should be noted that seven TCE
concentrations exceeded the range of the high curve but
were not diluted and reanalyzed. These results are
flagged. Because these sample results exceed 15 ppb, well
above the MCL of 5 ppb, there is no effect on project
conclusions.
Continuing calibration verifications (CCVs) at the 0.5 ppb
level frequently exceeded the QAPP specified criteria (80-
120%) for TCA in the effluent samples. Less frequently,
0.5 ppb CCVs exceeded the QAPP specified criteria for
CT and PCE. The acceptable CCV range was raised to 70-
130% because the affect on data quality was thought to be
minimal. Because sample results for TCA, CT and PCE
are well below the respective MCLs, there is no effect on
project conclusions.
A 5.0 ppb standard was used to check the adequacy of the
calibration curve for TCE. No 5.0 ppb standard was
performed for data sets 1 or 15, but the 0.5 ppb standard
was performed and the TCE CCV was within the 70-130%
range. All 5.0 ppb CCVs met QAPP specified criteria for
TCE (for other data sets). Project conclusions are not
impacted.
All EDB CCV results met the QAPP specified criteria.
4.4.3.1.6 Data Validation
A validation review of the analytical data for the
groundwater samples was conducted to ensure that all
laboratory data generated and processed are scientifically
valid, defensible, and comparable.
A data quality assessment was conducted to incorporate
the analytical data validation results and the field data
quality QC results, evaluate the impact of all QC measures
on the overall data quality, and remove all unusable values
from the investigation data set. The results of this
assessment were used to produce the known, defensible
information used to define the evaluation findings and
derive conclusions.
38
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Section 5
References
1. U.S Environmental Protection Agency. 1996.
Demonstration Plan for Sprinkler Irrigation as a VOC
Treatment and Disposal Method.
2. Spalding, Roy F. And Burbach Mark E. 1994.
"Sprinkler Irrigation: A VOC Remediation Alterna-
tive." Journal of the Franklin Institute, 1994. Vol.
331A, pp. 231-241.
3. Office of Federal Register. 1993. Code of
Federal Regulations Title 40, Protection of Environ-
ment. U.S. Government Printing Office, Washing-
ton, D.C. July 1993.
4. Florida Agricultural Information Retrieval
System (http://www.agnic.org/agdb/fairs.html).
5. STATKING Consulting, Inc. 1997. Nebraska
Demonstration Project for Sprinkler Irrigation:
Hastings Irrigation Water Contamination Study.
39
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Appendix A
The following list of questions relating the sprinkler
irrigation SITE demonstration was presented to state
reviewers from California, Florida, New Mexico, and
Nebraska.
40
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Table A-l. Sprinkler Irrigation Technology Implementation Factors - State Responses
Factor (Question) California
Florida
New Mexico
Nebraska
Is irrigation
appropriate for
this state?
Depends on the
amount of
rainfall. During
some times of
the year, the
ground is
saturated and
water runoff
may be a
concern.
Irrigation is a
good method.
There usually
is not a
problem
associated
with runoff.
Irrigation is very common in
Nebraska. The demonstration
site is currently used for
production and has been
previously irrigated.
crop
Is the irrigation
groundwater
pumping rate a
concern?
Will irrigation
contain the
groundwater
plume?
Would the use of
solvent
contaminated
groundwater have
an adverse affect
on crop
production?
Modeling will be
required to
account for
mounding
effects.
The pumping rate for irrigators
in Nebraska often range from
500-1000 gpm due to the
productive aquifers.
Groundwater use is regulated
by the state and each
irrigation well must be
registered. An existing
irrigation well was used for the
SITE demonstration.
A modeling analysis
previously performed at the
Hastings location predicted
the irrigation pumping at the
rates proposed would contain
the plume. The modeling
evaluated whether seasonal
pumping of the irrigation well
at the higher irrigation rates
would act in the same manner
as lower rate year-round
remediation pumping.
If the demonstration goals are
achieved, the water that
reaches the crop and the
ground will meet drinking
water standards. The health
department (and others) have
indicated that the plants do
not accumulate VOCs.
41
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Table A-l. Sprinkler Irrigation Technology Implementation Factors - State Responses (continued)
Factor (Question) California
Florida
New Mexico
Nebraska
What are the
state regulations
and concerns for
air emissions?
How does the site
specific air
modeling
employed for the
SITE
demonstration
compare with
other situations?
Permit
requirements
are 1 5 Ibs/day
and 800
Ibs/year.
Permits are
site-specific. A
permit is
required for
non-petroleum
sites.
Currently uses
the
deterministic
method.
No permit is
required as
long as the
emissions are
below 10
Ibs/hour or 1 0
tons/year.
Will accept
the use of an
EPA air
dispersion
model (air
and risk).
The mass emission threshold
is 2.5 tons/year for permitting
(1 ton/year for the
demonstration scenario).
Actual data were used, where
possible, including
contaminant concentrations
from previous testing, actual
physical dimensions of the
irrigation system, and actual
distances to exposure points.
The calculation methods were
standard EPA procedures for
risk assessment. A standard
EPA air dispersion model was
also used. It is anticipated
that these models could be
used to evaluate other
Would air
monitoring be
required?
Could get
a permit to
construct.
Monitoring
would
probably
be
required.
"Up front"
modeling would
probably be
required.
Precautionary
"up front"
modeling.
scenarios.
Not typically.
What are the
operational
concerns?
Manifold piping;
evenly
distributed flow
through the
nozzles; high
water tables
may require that
the system be
shut off for a
while.
The control of leaks and non-
spray discharges.
42
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Table A-l. Sprinkler Irrigation Technology Implementation Factors - State Responses (continued)
Factor (Question) California
Florida
New Mexico
Nebraska
Would there be
concern regarding
recharge to the
aquifer?
Would RCRA of
Land Disposal
Regulations be a
concern?
Should there be
concern about the
non-destruction of
VOCs?
Are there any
operational
considerations
that may limit the
application of the
technology?
Would the system
be able to strip
VOCs other than
those being
evaluated through
the SITE
demonstration?
Typically,
drinking water
standards are in
force.
However, If a
determination
that the
discharge is
surface water,
then NPDES
regulations
apply.
Site specific.
The target
reduction is
90%.
Year round
irrigation in the
northern part of
the state.
Not a
concern.
Site specific.
More stringent
standards for
sites located
in the city (i.e.
Albuquerque)
than for
remote sites.
Large
temperature
fluctuations.
Altitude.
Irrigation will
occur during
the summer.
No. The predicted
performance indicates that the
discharged water would meet
drinking water standards.
No. The LDRs are greater
than the MCLs.
Literature indicates that the
VOCs naturally degrade in air
and sunlight, although the
degradation rate depends on
the compound.
Rainfall and temperature.
Henry's Law may be used to
predict how easily a
compound may be stripped
from water.
43
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Appendix B
44
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Table B-l. Process Measurements - Sprinkler Irrigation SITE Demonstration
Process Measurement
Barometric Pressure, mm Hg
Barometric Pressure, mm Hg
Wind Direction
Wind Direction
Wind Speed, mph
Wind Speed, mph
Water Temperature," F
Water Temperature," F
Water Temperature, ° F
Water Temperature," F
Water Pressure, psi
Water Pressure, psi
Water Pressure, psi
Water Pressure, psi
Air Temperature, ° F
Air Temperature, ° F
Air Temperature, ° F
Air Temperature, ° F
PH
PH
PH
PH
Humidity, %
Humidity, %
Humidity, %
Humidity, %
Flowrate, gpm
Flowrate, gpm
Flowrate, gpm
Flowrate, gpm
Run1
(Morning)
29.83
170
170
09
011
59.5
58.5
58.5
59.0
34
34
34
34
79
80
81
81
7.08
7.09
7.11
7.11
77
77
77
74
1150
1150
1150
1150
Value
Run 2
(Noon)
29.81
29.80
190
170
09
10
59
60
60
58.5
35
35
35
35
90
91
91
91
--
63
63
63
62
1150
1150
1150
1150
Run 3
(Evening)
29.79
190
Variable
07
04
60.5
60
59
59
34
34
34
34
96
93
93
92
7.09
8.55
6.57
55
62
65
63
1150
1150
1150
1150
45
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Appendix C
Project Objectives for Region 7 Sampling
The purpose of the sampling event conducted by Region 7
was to collect groundwater split samples during the SITE
Demonstration from irrigation well 1-49 and to analyze the
samples for chlorinated solvents and EDB. The Region 7
results were compared to the analytical results obtained by
NRMRL to determine any bias in the analytical methods
and preservation techniques used by NRMRL.
Elevated levels of VOCs were present in the influent
samples and very low levels of VOCs were present in the
samples collected after the water was discharged through
the spray irrigation system. The information from the
SITE Demonstration was evaluated by EPA's Regional
office for inclusion in this Innovative Technology
Evaluation Report.
Introduction
Three influent and nine effluent groundwater samples
were collected and analyzed. The effluent samples were
collected from locations 10, 11 and 12, which were
beneath the nozzles with the largest openings. EPA
Region 7 selected these locations as the locations where
the irrigation system would most likely fail to adequately
strip the VOCs from the water.
Site Description
The North Landfill/Far-Mar-Co subsite is located in
Hastings Nebraska. Since 1983, EPA has been
investigating the groundwater contamination in and
adjacent to the city of Hastings. Contaminants associated
with the North Landfill subsite include TCE, TCA, PCE,
DCE and vinyl chloride (VC). Contaminants associated
with the Far-Mar-Co subsite include CC14 and EDB. 1-49
is an irrigation well located down gradient from both of
these subsites. Three tests have been performed on this
well. The first test was a pump test and the second and
third tests were sprinkler irrigation studies. The first test,
which investigated the effects of the sprinkler head design
in relation to the volatilization of VOCs, was performed
by the University of Nebraska. The second test was
conducted by Region 7 and the third test was the SITE
Demonstration which was conducted in July 1996.
Site History
The Hastings Groundwater Contamination site includes
seven subsites. The information collected for this limited
study was from one irrigation well, 1-49. The SITE
Demonstration, forms the basis for the evaluation of the
sprinkler irrigation performance for remediation of
groundwater contaminated sites. The demonstration
consisted of three separate sampling events, one each in
the morning, noon, and evening. EPA-Region 7 collected
one influent and three effluent groundwater samples
during each sampling event. All samples collected by the
Region 7 personnel were analyzed using Regional
protocol.
Target Compounds
Influent groundwater samples were analyzed for VOCs at
standard CLP detection limits. Effluent groundwater
samples were analyzed for VOCs at 1 ppb detection limits.
Detection limits for EDB was 0.05 ppb for all samples.
The compounds of interest were vinyl chloride,
methylene chloride, 1,1-dichloroethene, 1,2
dichloroethene (both cis and trans), 1,2-dichloroethane,
carbon tetrachloride, ethylene dibromide, trichloroethene,
1,1 ,2-trichloroethane, tetrachloroethene, and 1 ,1 , 1-
trichloroethane.
The detection limit for the influent samples ranged from 5-
10 ug/L. The detection limit for effluent samples was 1
46
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Hg/L. The detection limit for ethylene dibromide (influent
and effluent) was 0.05 ug/L.
All equipment used for the collection of the water samples
were prepared in accordance with Regional SOP
#OPQAM. Sample containers, preservation, and holding
times met Regional SOP # 2130.4B. Sample shipment
was by government owned vehicle in accordance with the
procedures identified in SOP #2130.6A. Sample custody
and documentation of field activities followed SOP
#2130.2Aand#2130.3B.
Sample Network and Rationale
Procedures identified in EPA's Region 7 draft document
no. 1200.4A Generic OA Project Plan for Oversight and
Split Sample Collection at CERCLA PRP Activities.
Section 5 were followed for the collection of groundwater
samples. Field QA elements followed SOP #2130.3B.
Laboratory QC elements followed SOP #1610.1C. The
frequency of QC checks followed SOP #2130.3B. Control
limits and corrective actions followed SOP #2110.2C.
In fluent Samples
Three influent groundwater grab samples were collected
from 1-49. One grab sample was taken at the beginning of
each sampling event (3 total). These samples were
analyzed using the Region's method (WV, W13 and
WV69) and detection limits. The detection limit for EDB
analyzes was 0.05 (ig/L.
No influent field duplicate samples were collected.
Effluent Samples
Nine effluent split groundwater samples were collected
from the irrigation system. These samples were collected
at approximately the same time as those collected by
NRMRL personnel. The samples were collected at the far
end of the irrigation system where the water spray was the
strongest. Duplicate water samples were collected in 40-
mL VOA vials, labeled, and placed in a cooler.
Field sheets and sample tags, which were supplied by the
Region, provided the following sample information:
1. Sample number (see corresponding field sheet)
2. Sample type (i.e. influent or effluent, collected)
3. Date and time of collection
Bottles, holding times, and preservation requirements for
these analysis are shown below:
Groundwater samples were collected directly into sample
containers and placed on ice. No acid preservatives were
used with any of these samples. Field sheets were
modified to reflect this fact. No BTEX compounds were
present in the samples.
Each sample was accompanied by a field sheet. The
shipment of the samples from the field to the EPA Region
7 laboratory was accompanied by a chain-of-custody
sheet.
Analytical Methodology
These samples were analyzed using Regional protocol
identified in SOP #OPQAM for routine VOCs, low level
VOCs, and EDB.
Target Compounds
Influent groundwater samples were analyzed for VOCs at
a detection limit of 5 ug/L and were analyzed using the
"WV" method. These samples contained TCE at a
concentrations that ranged from 200-1000 ug/L and EDB
at a concentration of approximately 1 ng/L. Several other
VOCs were present at a concentration that ranged from 5-
20 ug/L. Effluent groundwater samples were analyzed for
VOCs at a lug/L detection limit using the W13 protocol.
These low levels of detection were needed to validate the
percent removal efficiencies of the spray irrigation
system. The detection limit for EDB was 0.02 ug/L using
the WV69 protocol.
Data Review, Validation, and Reporting
Level 4 data were required for this sampling event. The
Regional methods cited were used. The Regional
laboratory followed Regional SOP #1610.1C during the
review process and to evaluate the acceptability of the data
based on these criteria. Data deliverables followed SOP
#2119.2C. Data generated from this sampling event were
used in the evaluation of split samples generated by
NRMRL. The results were compared to the NRMRL
analytical results to determine if NRMRL's methods were
within 20 % of the results generated using the Region 7
analytical protocols. If the data indicated that the NRMRL
47
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results were not similar to the Region 7 results, a more
through evaluation of the analytical procedures was
conducted.
A performance evaluation (PE) sample was prepared
using the following water supply audits: WS035, CONC1;
WS035 CONC2, and WS034 CONC4. The true value (ug/
L)of each compound (with control limits) is as follows:
TCA-8.78
CT-10.8
TCE-6.13
EDB-0.051
PCE-4.93
CL5-12;
CL 8.2-12.9;
CL 3.6-8.5;
CL 0.04-0.06
CL 3-6.8
The MCL for each compound was: TCA - 200 ug/L, CT,
TCE, and PCE - 5 ug/L, and EDB 0.05 ug/L.
Discussion of Results
All groundwater samples collected by the Region were
analyzed. Table 1 presents the analytical results for the
five compounds of concern (TCA, CT, TCE, EDB, and
PCE). Samples were collected during the morning (M),
noon (N), and evening (E) at locations 10, 11 and 12.
Influent samples were coded with an "ENF" symbol.
Detection limits are shown in the table followed by a "U."
EPA-NRMRL analytical results are denoted by the prefix
"NRMRL."
Comparison of EPA-NRMRL and EPA-
Region 7 Results
Acceptable results were defined as those results for
positive compounds above the MCL (within 20%) which
was established by Region 7 as the action level.
Morning-Influent
EPA-NRMRL collected and analyzed several samples
from the morning effluent. For this comparison, an
average of the results were compared to one sample
collected by EPA-Region 7. The data indicates that the
TCA results were within 10%. For CT, EPA Region 7
indicates a detection limit of 4U and EPA-NRMRL
indicates a presence at 5.2. These results are acceptable.
The TCE results were within 4%. EDB results were within
a range of 22-28% and the PCE the results were within
10%. Overall these results are acceptable.
Effluent
There were no locations where groundwater samples were
collected and analyzed by both EPA-NRMRL and EPA-
Region 7 laboratories. EPA Region 7 compared these
results with the second site sampling event and found that
the results compare favorable to previous test results.
Noon-Influent
The data indicates that the TCA results were within 17%.
For CT, EPA Region 7 results indicate a non-detect at 4U;
EPA-NRMRL results indicate a presence at 4.8, within
20%. The results for TCE were within 4%. The results for
EDB were within a range of 26-36%. The PCE results
were within 10%. Overall, these results are acceptable.
Effluent
There were two locations from which samples were
collected and analyzed by both laboratories. The TCA
results compare as follows: for location 11, height 1
(closest to the ground), EPA Region 7 indicates a non-
detect with a detection limit of 0.6U and EPA-NRMRL's
result indicates a positive at 0.055C. These results are
acceptable. For CT, EPA-Region 7 indicates non-detect at
0.2U and EPA-NRMRL indicates a presence at 0.043.
These results agree. For TCE. EPA-Region 7 indicates a
presence at 2 and EPA-NRMRL indicates a presence at
>15J. These results do not agree and should be verified.
For EDB, the EPA Region 7 result is non-detect at 0.009U.
The EPA-NRMRL result indicates a presence at 0.029L.
These results are acceptable. For PCE, the EPA-Region 7
result indicates a non-detect at 0.03U. The EPA-NRMRL
result indicates a presence at 0.068. These results are
acceptable.
The TCA results compare as follows: for location 10,
height 1 (closest to the ground), EPA Region 7 indicates a
non-detect with a detection limit of 0.6U and EPA-
NRMRL' s result indicates a positive at 0.1 IS. These
results are acceptable. For CT, EPA-Region 7 indicates a
non-detect at 0.2U and EPA-NRMRL indicates a presence
at 0.083S. These results agree. For TCE, EPA-Region 7
indicates a presence at 5 and EPA-NRMRL indicates a
presence at 4.3S. These results are acceptable. For EDB,
EPA Region 7 results indicate a presence at 0.017 and
EPA-NRMRL results indicate a presence at 0.048S. These
results are acceptable. For PCE, EPA-Region 7 results
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Table C-l. SITE Demonstration Comparison of Region 7 Data and EPA-NRMRL
LOCATION TCAfog/L) CT fcg/L) TCE fog/L) EDB faq/L) PCE foq/L)
M-10-H1
M-l 1-H1
M-12-H1
N-12-H1
N-l I-HI
NRMRL N-l 1-H1
N-10-H1
NRMRL N-10-H1
PE
NRMRL PE(AVE)
E-l 1-H1
NRMRL E-l I-HI
E-l 0-HI
NRMRL E-IO-HI
E-12-HI
NRMRL E-12-HI
M-INF
NRMRL M-INF-AV
N-INF
NRMRL N-INF-AV
E-INF
NRMRL E-INF-AV
Notes:
" See Table 9.
0.6U
0.6U
0.6U
0.6U
0.6U
0.055 D
0.6U
0.11 S,D
9
6.2
0.6U
0.088
0.6U
0.11
0.6U
0.29
7
7.6
6
7.0
6
7.1
0.2U
0.2U
0.2U
0.2U
0.2U
0.043
0.2U
0.083 S
11
9.2
0.2U
0.075
0.2U
0.10
0.2U
0.29
4u
5.2
4u
4.8
4u
4.8
4
2
6
7
2
>15H
5
4.3 s
7
6.0
5
4.3
5
6.2
10
8.5
500
516
520
544
500
530
0.01 U
0.011
0.023
0.019
0.009U
0.029 L
0.017
0.048 S
0.053
0.057
0.015
0.041
0.012
0.056
0.04
0.22"
1.4
1.8
1.1
1.5
1.1
1,6
0.3U
0.3U
0.3U
0.3U
0.3U
0.068
0.3U
0.11 s
5
4.6
0.3U
0.10 D
0.3U
0.12 D
0.3U
0.28
7
7.6
7
7.7
7
7.5
49
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indicate a non-detect at 0.03U and EPA-NRMRL's results
indicate a presence at 0.11S. These results are acceptable.
Evening - Influent
The data indicate that the TCA results were within 18%.
For CT, EPA Region 7 results indicate a non-detect at 4U
and EPA-NRMRL results indicate a presence at 4.8,
within 20%; the TCE results were within 4%, the EDB
results were within a range of 31-45%, and the PCE results
were within 10%. The results for EDB should be verified,
otherwise the results for the are acceptable.
Effluent
There were three locations from which samples were
collected and analyzed by both laboratories. The TCA
results compare as follows: for location 11, height 1
(closest to the ground) EPA Region 7 indicates a non-
detect with a detection limit of 0.6U and EPA-NRMRL's
result indicates a positive at 0.088C. These results are
acceptable. For CT, EPA-Region 7 indicates non-detect at
0.2U and EPA-NRMRL indicates a presence at 0.075C.
These results agree. For TCE, EPA-Region 7 indicates a
presence at 5 and EPA-NRMRL indicates a presence at
4.3. These results agree. For EDB, EPA Region 7 result
was 0.015 and EPA-NRMRL results indicates a presence
at 0.041. These results are acceptable since they were
below the MCL of 0.05. For PCE, EPA-Region 7 results
indicate a non-detect at 0.03U and EPA-NRMRL's results
indicate a presence at 0.103C. These results are
acceptable.
Effluent
For TCA at location 10, height 1 (closest to the ground)
EPA Region 7 indicates a non-detect with a detection limit
of 0.6U and EPA-NRMRL's result indicates a positive at
0.114C. These results are acceptable. For CT, EPA-
Region 7 indicates a non-detect at 0.2U and EPA-NRMRL
indicates a presence at 0.102. These results agree. For
TCE, EPA-Region 7 indicates a presence at 5 and EPA-
NRMRL indicates a presence at 6.2. These results should
be verified. For EDB, EPA Region 7 results indicate a
presence at 0.012 and EPA-NRMRL results indicates a
presence at 0.056. These results are acceptable. For PCE,
EPA-Region 7 results indicate a non-detect at 0.03U and
EPA-NRMRL's results indicate a presence at 0.12C.
These results are acceptable.
For TCA at location 12, height 1 (closest to the ground),
EPA Region indicates a non-detect with a detection limit
of 0.6U and EPA-NRMRL's result indicates a positive at
0.29. These results are acceptable. For CT, EPA-Region
7 indicates a non-detect at 0.2U and EPA-NRMRL
indicates a presence at 0.29. These results agree. For TCE,
EPA-Region 7 indicates a presence at 10 and EPA-
NRMRL indicates a presence at 8.5. These results are
acceptable. For EDB, EPA Region 7 results indicate a
presence at 0.04 and EPA-NRMRL results indicates a
presence at 0.22. These results need to be verified. For
PCE, EPA-Region 7 results indicates a non-detect at
0.03U and EPA-NRMRL's results indicate a presence at
0.28. These results are acceptable. A comparison of
Region 7 and EPA-NRMRL data are shown in Table 1.
Performance Evaluation Sample
A PE sample was analyzed by each laboratory. The results
indicate that both laboratories were within the control
limits for all compounds. Sample information is provided
in Table 2.
50
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Table C-2. Sample information - Region 7
Preservation
Parameter Container (Holding Time)
VOCs-WV 2 x 40 mL VGA Ice to 4 C
Vial (14 Days)
vocs-w13 4x40mLVOA ice to 4 C
Vial (14 Days)
VOCs- 2 x 40 mL VOA Ice to 4 C
VW69 Vial (14 Days)
51
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Appendix D
Sample Size Estimation
52
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f* UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
NATIONAL EXPOSURE RESEARCH LABORATORY
* * CINCINNATI. OH *5268
"
Date: May 22, 1996
RESEARCH AMD OevElOPMEWT
Subject: Sample Size Estimation for the Nebraska Sprinkler
Irrigation Experiment
To: Randy Parker, Environmental Engineer
Remediation and Contamination Branch
Land Remediation and Pollution Control
National Risk Management Research Laboratory ,,
From: Florence A. Fulk, Statistician ^yrF
National Water Quality Assurance Programs Branch
Ecological Exposure Research Division
A study to assess the effectiveness of sprinkler irrigation
in removal of carbon tetrachloride (CT) , trichloroethylene (TCE)
and dibromoethane (EDB) is planned for June 1996. AS part of the
experimental design, the number of samples needed to determine if
the average levels of CT, TCE or EDB exceed the maximum
contaminant level (HCD) were estimated.
Due to the nature ofthe sampling device a stratified random
sampling plan was adopted to reduce the variability among samples
and consequently reduce the total number of samples needed for
the study. At a sample point alongthe irrigation arm, a
sampling device collects samples at four heights. prom previous
studies, it was shovn that the levels of the contaminants
decreased with decreasing height due to volatilization of the
compounds. Four strata for sampling were thus chosen, one for
each of the heights along the sampling device. Twelve sampling
devices will be placed equi-distant along the irrigation arm and
three sampling events will occur within a day for a total of 144
collected samples, 36 at each of the four heights.
To estimate the number of samples to be analyzed from the
total of 144 collected samples, an estimate of the variability
within each strata for CT, TCE and EDB is necessary. Samples
that were collected on 8/23/95 and analyzed forCT, TCE and EDB
were used to obtain the estimates. (Copy of data attached.) The
variability estimates are limited by trie fact that the samples
were collected on a single day at a single time point and are
probably less than if the samples were taken at different times
across a day. For each analyte and height, the coefficient of
variation (CV) was calculated from the data. Since the majority
of the data for CT was below the detection limit, the same CV
values for TCE were used forCT. The CV was then applied to the
MCL for each analyte to obtain an estimate for »2 at each height.
The s2 estimates at each height were utilized in a modified
formula forestimating the variability of a stratified sample to
53
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acquire the overall variability estimate for each analyte1. To
calculate the sample size, an alpha level of 0.05 and a beta
level of 0.01 were chosen. This corresponds to a significance
level of 95% and a power of 99%. The amount of difference, or
effectsiz«,from the HCL to detect was 1 jig/L for CT and TCE
and 0.01 nq/l forEDB. The variability estimate, normal table
values of alpha and beta, and the effect size vere applied to the
formula for sample size estimation for each analyte . For each
of CT, TCE and EDB, the estimated total number of samples for
analysis was calculated to be 32. To account for additional
variability from sampling at different time points, the
recommended number of total samples is 40. The forty samples
would be evenly distributed across each strata, ten samples from
each sampling height. The samples would be randomly selected
from the 36 samples collected at each height.
Modified formula for variability of a stratified sample:
ST2 - .25 S Sh:
Formula for estimating sample size:
n - St2 (Z. + Z,)2/ A2
7. Cochran, William G. (1977), Stapling Techniques, 3rd. eel. ,
John Wiley & Sons, New York, New York.
2. Lipsey, MarkW. (1990), Design Sensitivity: Statistical Power
for Experinen tal Research, SAGE Publ ications Inc . , Newbury
Park, California.
cc: M. Kate Smith
Robert Graves
R/l
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Appendix E
Statistical Analysis Report
55
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NEBRASKA DEMONSTRATION PROJECT
FOR SPRINKLER IRRIGATION
HASTINGS IRRIGATION WATER CONTAMINATION STUDY
Statistical Analysis Report
Prepared for
US Environmental Protection Agency
26 W. M. L. King Drive
Cincinnati, OH 45268
Prepared by
STATKING Consulting Inc.
780 Nilles Road - Suite E2
Fairfield, OH 45014
(5 13) 858-2989
Dermis W. King, PhD Date
STATKING Consulting Inc.
REVISED FINAL VERSION -12/12/97
56
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CONFIDENTIALITY STATEMENT
The following description will constitute the final report of the data analysis on the
Hastings Irrigation Water Contamination Study data. Any information contained herein
is strictly confidential and is not to be released to anyone without written consent of the
US EPA. Upon final acceptance of this report, the US EPA becomes sole owner of the
information contained. All written and electronic information concerning this study will
be kept on file at STATKING Consulting for a period of one year.
The report will be divided into two parts. The first is a general summary of the statistical
analysis of the data. The second part of the report is a technical summary and
justification of the statistical methods used to analyze the data.
STATKING Consulting Inc. Page 2 of 12 Hastings Irrigation Water Study
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TABLE OF CONTENTS
Page
Title Page
Confidentiality Statement 2
TABLE OF CONTENTS 3
Table of Contents - Tables -4
1. Data Analysis Summary -5
1.1 Background .5
Analyzed Population, Sampling Plan and Strata Definitions -5
Response Variables .5
1.2 Results of Statistical Analyses of VOC Contaminants Data 6
Results of Statistical Analyses of Data From All Heights 6
Results of Statistical Analyses of Data From Height One 6
Power Analysis .7
2. Technical Notes 8
2.1 Stratified Random Sampling Estimators .-8
2.2 Confidence Intervals.. 8
2.3 Hypothesis Tests .9
2.7 Power Calculations 9
2.5 Other Technical Notes.. 10
REFERENCES 11
APPENDIX A 12
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TABLE OF CONTENTS - Tables
Table
Data Listing Al
TCA Statistical Analysis - Complete Data Set A2
CT Statistical Analysis - Complete Data Set A3
TCE Statistical Analysis - Complete Data Set A4
EDB Statistical Analysis - Complete Data Set A5
PCE Statistical Analysis - Complete Data Set A6
TCA Statistical Analysis - Height One Data Only A7
CT Statistical Analysis - Height One Data Only A8
TCE Statistical Analysis - Height One Data Only A9
EDB Statistical Analysis - Height One Data Only A10
PCE Statistical Analysis - Height One Data Only All
TCA Power Curve for Detecting Significance Above MCLs A12
CT Power Curve for Detecting Significance Above MCLs A13
TCE Power Curve for Detecting Significance Above MCLs A14
EDB Power Curve for Detecting Significance Above MCLs A15
PCE Power Curve for Detecting Significance Above MCLs A16
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1. DATA ANALYSIS SUMMARY
1.1 Background
The main objective of this experiment was to determine the efficacy of the sprinkler
irrigation system to treat ground water contaminated with volatile organic compounds
(VOCs) to concentrations that average below the acceptable maximum contaminant
levels (MCLs). The objective was evaluated through the collection and analysis of
samples from the sprinkler mist. The data obtained from the experiment was statistically
analyzed to statistically determine if the average concentrations of VOCs exceed the
stated MCLs. The study was conducted by the US EPA at the USEPA Research Station
in Hastings, NE in the summer of 1996.
Analyzed Population, Sampling Plan and Strata Definitions
The target population for this study was the water released from the particular
irrigation arm under study at the Hastings, NE site. All statistical estimation and
inference described in this report is relative to this and only this population.
It has been shown in previous studies that levels of VOCs tend to decrease as the
irrigation water falls from the pivot onto the field. Since VOC levels in samples
collected from a specific height will tend to be similar, the population of irrigation water
coming from the pivot was divided into homogeneous groups known as strata
corresponding to the height above ground where the water was sampled. By dividing the
population into strata before sampling, a better estimate of the mean level of VOCs can
be obtained. The statistical term for this type of sampling setup is stratified random
sampling.
For this experiment, four heights or strata were identified. The sampling of the
irrigation water was conducted at four different heights ranging from just under the pivot
to ground level. The data collected from each of these heights was then sampled in order
to obtain an estimate of the mean level of a particular VOC for the pivot.
Response Variables
The VOCs recorded and statistically analyzed were 1,1,1-trichloroethane (TCA),
carbon tetrachlotide (CT), trichloroethylene (TCE), dibromoethane (EDB) and
tetrachloroethene (PCE). The response values were measured in parts per billion. A
listing of the data values collected and statistically analyzed is shown in appendix Table
Al. Samples N-S10-H 1, M-S 11-H3 and M-S9-H4 failed to meet the quality assurance
(QA) criteria and were dropped from the data set before the statistical analyses were
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conducted. The data for these samples are not shown anywhere in this report. The MCL
for each of the VOCs analyzed is given in the following table.
Table 1. Maximum Contaminant Levels for VOCs
Contaminant
TCA
CT
TCE
EDB
PCE
MCL
200ng/L
5ng/L
5ng/L
.05ng/L
5ng/L
1.2 Results of Statistical Analyses of VOC Contaminants Data
Tables A2-A11 in the appendix show the results of the data analysis of the VOC data
collected during this study. Statistical analyses were performed first on all data and then
on data sampled from height one only.
Results of Statistical Analyses of Data From All Heights
Tables A2-A6 in the appendix summarize the results of the hypothesis tests conducted
on the VOC data from all sampling heights. From Table A2, TCA levels were shown to
be well below the MCL of 200 jig/1 (p= 1.0000). A 95% confidence interval on the mean
level of TCA was (.21 ,.25). The same was true of CT and PCE VOCs shown in Tables
A3 and A6 (p=l .0000,1 .0000, respectively). For TCE, shown in Table A4, the mean
level was shown to be significantly greater than the MCL of 5 ng/I (p=.0001). A 95%
confidence interval on the mean level was (11.98,14.13). From Table A5, the mean level
of EDB was shown to be significantly larger than the MCL of .05 jig/1 (p=.0028). A
95% confidence interval on the mean level was (.06,. 10).
Results of Statistical Analyses of Data From Height One
During the evening sampling period, samples were collected at all twelve sampling
locations along height one of the sampling mechanism. Tables A7-A11 in the appendix
summarize the results of the hypothesis tests conducted on the VOC data for this data.
From Table A7, TCA levels were shown to be well below the MCL of 200 ng/1
(p=l .000). A 95% confidence interval on the mean level of TCA was (.09,. 15). The
same was true of CT and PCE VOCs shown in Tables A8 and Al 1 (p=l .0000, 1 .0000,
respectively). For TCE, shown in Table A9, the mean level was shown to be
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Page 6 of 12
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significantly greater than the MCL of 5 ^g/1 (p=.0219). A 95% confidence interval on
the mean level was (5.02,6.55). From Table A10, the data collected provided no
indication that the mean level of EDB was significantly larger than the MCL of .05 ng/1
(p=.0959) at the .05 level. A 95% confidence interval on the mean level was (.04,.09).
Power Analysis
The results of this study can be used to give indication of the power of the hypothesis
tests conducted on the data. Power is the probability of detecting a significant difference
between the mean level of a VOC and its MCL if that difference, in fact, exists. For each
VOC, power calculations were conducted for ranges of differences between the
population mean and the MCL for the particular VOC using the standard deviations and
sample sizes observed in the current study.
Tables A12-A16 in the appendix give the power curves for each of the VOCs
observed in this study. From these curves, the sensitivity of the hypothesis test can be
examined. The most interesting difference on these tables is the smallest difference
between the population mean and the MCL that can be detected 80% or greater of the
time by the hypothesis test. These values are sometimes called the minimum detectable
differences for the hypothesis test. These differences are summarized in the Table 2.
Table 2. Minimum Detectable Differences for Tests on VOCs
VOC
TCA
CT
TCE
EDB
PCE
Min. Detectable Difference
.0036
.0036
.2000
.0036
.0036
From Table 2, it can be concluded that, with the current sample sizes, minute differences
between the mean level of a VOC and its MCL can be detected if, in fact, those
differences exist.
STATKING Consulting Inc.
Statistical Analysis Report
Page 7 of 12
Hastings Irrigation Water Study
62
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2. TECHNICAL NOTES
2.1 Stratified Random Sampling Estimators
It has been shown that levels of VOCs tend to decrease as the irrigation water falls
from the pivot onto the field. Since VOC levels in samples collected from a specific
height will tend to be similar, the population of irrigation water coming from the pivot
can be divided into homogeneous groups known as strata corresponding to the height
above ground where the water is to be sampled. By dividing the population into strata
before sampling, a better estimate of the mean level of VOCs can be obtained. The
statistical term for this type of sampling setup is stratified random sampling.
For this experiment, four heights or strata were identified. The sampling of the
irrigation water was conducted at four different heights ranging from just under the pivot
to ground level, The data collected from each of these heights was then sampled in order
to obtain an estimate of the mean level of a particular VOC for the pivot.
Levy and Lemeshow (1991) have shown that an estimate of the mean level of a
response variable using a stratified random sampling plan is given by
where xk is the mean of the response variable in strata h, Nh is the size of strata h, N is
the size of the population sampled and L is the number of strata in the population. Note
that this estimate is a weighted average of the strata means. The estimated variance of
this estimate is
where s\ is the estimated variance of the response data in strata h and nk is the sample
size in strata h. The estimated standard error of the estimate is
2.
2 Confidence Intervals
It is also of interest in this study to give some measure of the reliability of the
estimated mean levels of VOC in the irrigation water. This can be done using confidence
intervals. A confidence interval is an interval estimate of the population mean VOC
STATKTNG Consulting Inc, Page 8 of 12 Hastings Irrigation Water Study
Statistical Analysis Report
63
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content which will contain the true population mean VOC a prespecified proportion of
the time.
Cochran (1954) and Levy and Lemeshow (1991) have shown that for normally
distributed data and/or large samples, a 100( l-a)% confidence interval on the population
mean under stratified random sampling is given by
In repeated sampling, this interval will contain the population mean 1 00( l-a)% of the
time.
2.3 Hypothesis Tests
The main statistical objective of this study was to determine if VOC content of the
irrigation water was significantly below acceptable maximum contaminant levels
(MCLs). This situation requires a one-side hypothesis test that the mean level of the
VOC is below the MCL.
Snedecor and Cochran (1980) have shown that a large sample test of the one-sided
hypotheses
H0:nn0,
where n0 is the MCL for the particular VOC being tested, can be conducted using the
test statistic
and rejecting when Z > Z,.a where Z,_a is the ( 1 -a)x 100th percentile of the standard
normal distribution.
2. 7PoweiCtlculations
Power calculations were computed using the central and noncentral T distributions.
The power of a statistical hypothesis tests is the probability of rejecting H0 assuming HQ
is false. For a one-sided, one sample hypothesis test on the mean level, this probability is
given by
Power = ^(Reject H0\H0 is false) = P(T>/,__,.« \H9 is false)
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where 71* is a non central T random variable with n-f degrees of freedom and non
centrality parameter
/i is the total number of subjects, ^Ois the hypothesized population mean value and CT is
the standard deviation of the data. Power curve tables were constructed by computing
power for a range of A = n - n0 values using the sample size used in this study and the
standard deviations observed from this study. For a further discussion of power
calculations, see Guenther ( 1973).
2.5 Other Technical Notes
All computing was done using v6.11 of the SAS System on an IBM PC350 100MHz
personal computer running the OS/2 v3.0 operating system.
STATKING Consulting Inc. Page 10 of 12 Hastings Irrigation Water Study
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REFERENCES
Cochran, W.G. (1977). Sampling Techniques, New York, John Wiley & Sons, 3rd
edition.
Guenther, W.C. (1973). Concepts of Statistical Inference, New York, NY: McGraw-
Hill Book Company, 2nd edition.
Levy, P.S. and Lemeshow, S. (1991). The Sampling of Populations, New York, NY:
John Wiley & Sons.
Snedecor, G.W. and Cochran, W.G. (1980). Statistical Methods, Ames, IA: The Iowa
State University Press, seventh edition.
STATKING Consulting lac. Page 11 of 12 Hastings Irrigation Water Study
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Table Al. Nebraska Demonstration Project for Sprinkler Irrigation
US EPA - tUstingsflata
Data Listing
oes
1
2
3
4
5
6
7
8
9
10
11
12
13
U
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
3s
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
San?l« ID
M-S1-H1 (15)
M-S6-H1 (1)
M-S2-H1 (3)
M-S5-H1 (15)
N-S6-H1 (3)
N-S9-H1 (15)
N-S11-H1 (4)
E-Sl-tll (5)
E-S2-H1 (5)
E-S3-M1 (5)
E-S4-H1 (5)
E-S5-M1 (5)
E-S6-H1 (6)
E-S7-H1 (6)
E-S8-H1 (7)
E-S9-H1 (6)
E-S10-H1 (6)
E-S11-H1 (6)
E-S12-H1 <7)
M-S1-H2 (11
M-S6-H2 (15)
H-S5-H2 (3)
N-S6-H2 (3)
N-S7-H2 (3)
N-S12-H2 (15)
E-S2-H2 (5)
E-S5-H2 (5>
E-S8-H2 (6)
E-S9-H2 <6 7)
E-S10-H2 (15)
E-S11-H2 (6)
E-S12-H2 (15 16)
H-S4-H3 (1)
H-S6-H3 (1)
M-S7-H3 (1)
N-S2-H3 (3)
N-S6-N3 (15)
M-S10-H3 (4)
E-S4-H3 (15)
E-S5-H3 (5)
E-S8-H3 (6 7)
M-S1-H4 (1)
M-S2-H4 (15)
H-S4-H4 (15 161
M-S5-H4 (1)
V-S1-H4 (3)
N-S11-H4 (4)
N-S12-H4 (4 5)
E-S3-H4 (5)
E-SS-N4 (6)
E-S11-H4 (6 7)
HEIGHT
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
TCA
-------
Table A2. Nebraska Demonstration Project for Sprinkler Irrigation
US EPA nestings Data
Full Data Set
Contaminant: TCA
Strata One
Strata Strata Sample Overall Overall 95* Cl on the Z Sided P
Strata TCA Mean TCA SD Sire TCA Mean TCA SEN Mean TCA Statistic Value
1 0.11 0.05 19
2 0.18 0.05 13
3 0.25 0.04 9
i> 0.37 0.12 10 0.23 0.01 ( 0.21, 0.25.) -19977 1.0000
68
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Table A3. Nebraska Demonstration Project for Sprinkler Irrigation
VS EPA Mailings Data
Full Date Set
Contaminant: Cl
Strata One
Strati Strata Sanple Overall Jverrll 95% Cl on the 2 Sided P
Strata CT Mean CT SO Size CT Hean CT SEN Mean CT Statistic Value
1 0.05 19
2 1.11 US 0.05 13
3 0.20 0.03
4 0.30 0.08 II 0.19 0.01 ( 0.17, 0.21,) -481.2 1.0000
69
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Table A4. Nebraska Demonstration Project for Sprinkler Irrigation
VS EPA Hastings Data
Full Sate Set
Contaminant: TCE
Strata
1
2
3
4
strata
ICE Mean
ll.U.U
20109
Strrtr
TCE SO
2.51
6.00
Strata
Sample
Size
19
13
111
Overall
TCE Mean
13.06
Overall 95X Cl on the
TCE SEM Mean TCE
0.55 (11.98,14.13)
one
2 Sided P
Statistic Value
14.67 0.0001
70
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Table AS. Nebraska Demonstration Project for Sprinkler Irrigation
VS EPA Meetings Data
Full Data Stt
Contaminant: EDI
Strrtr One
Strata Strata Sample Overall Overall 9SX CI on the 2 Sided P
Strata EOB Mean EDB SD Size EBB Mean EDB SEX Mean EOB Statistic Value
1 0.06 0.04 19
2 13
3 O.OC 1.1! I.I! 9
4 0.11 0.03 10 0.08 0.01 ( 0.06, O.IOJ 2.77 0.0028
71
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Table A6. Nebraska Demonstration Project for Sprinkler Irrigation
VS EPA Hastins* Data
Full Date Set
Contaminant: PCE
Strata One
Strata Strata Sample Overall Overall 95* Cl on the 2 Sided P
Strata PCE Mean PCE SO Size PCE Mean PCE SEN Mean PCE Statistic Value
1 0.12 0.04 19
2
3 u i.n iff f.fi i) i
4 0.39 0.15 10 0.24 0.01 ( 0.22, 0.261 -428.5 1.0000
72
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Table A7. Nebraska Demon* teat ion Project for Sprinkler Irrigation
VS EPA - Nestings Data
Height One Date Only
Contaninant: TCA
Strata One
Strata Strrta Sample Overall Overall 95%Cl on the 2 Sided P
Strata TCA Mean TCA SD Size TCA Mean TCA SEN Mean TCA Statistic Value
1 0.12 0.06 12 0.12 0.01 (0.09,0.15) -13439 1.0000
73
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Table A8. Nebraska Demonstration Project for Sprinkler Irrigation
DS EPA - Hastings beta
Weight One Data Only
Cont«in«ms CT
Strrtr w e
Strata Strrtr Simple Overall Overall ?5S CI on the 2 Sided P
Strata CT M«ift CT SD Size CT Ke«n CT SEK Jfean CT Statistic Value
1 0.11 0.06 12 0.11 0.01 ( 0.08, 0.14) -337.4 1.0000
74
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Table A9. Nebraska Demonstration Project for Sprinkler Irrigation
DS EPA Hastings D»U
Height One Data Only
Contminant: TCI
Strata One
Strata Strata Sample Overall OveraJJ 95* CI on the 2 Sided P
Strata TCf Mean TCE SD Size TCE Mean TCE SEM Mean TCE Statistic Value
i 5.78 1.63 12 5.78 0.39 ( 5.02, 6.55) 2.02 0.0219
75
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Table A10. Nebraska Demonstration Project for Sprinkler Irrigation
VS EPA Hastings Data
Height One Data Only
Contsmfnant: EDS
Strata One
Stratr Strrtr Sample Overall Overall 95* Cl on the 2 Sided P
Strata EDB Hean EDS SO Size EDB Wean EDS SEW Mean EDB Statistic Value
1 0.07 0.05 12 0.07 0.01 ( 0.04, 0.09) 1.31 0.0959
76
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Table All. Nebraska Demonstration Project for Sprinkler Irrigation
VS EPA Hastings Date
Height One Data Only
Contaminant: PEE
Strrta One
Strata Strata Sai«ptt Overall Overall 95X Cl on the 2 Sided P
Strata PCE H««n PCE SO Size PCE Mean PCS SEN Mean PCE Statistic Value
1 0.13 0.03 12 0.13 0.01 ( 0.10, 0.15.) -397.0 1.0000
77
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Table A12. Nebraska Demonstration Project for Sprinkler Irrigation
IIS EPA Mattings Data
TCA Power Curve for Detecting Significance Above HCL8 , n* 51
Variable: TCA,
Sample Size: 51,
ANO Std. flev. 0.01
Difference from
Hypthesized Value
0
0.0002
0.0004
0.0006
0.0008
0.001
0.0012
O.OOU
0.0016
0.0018
0.002
0.0022
0.0024
PMR
0.050
0.066
0.086
0.111
0.140
0.174
0.212
0.255
0.302
0.353
0.407
0.462
0.518
0.0026
0.5741
0.0028
0.003
0.0032
0.0034
0.0036
0.0038
0.004
0.0042
O.OOU
0.0046
0.0048
0.005
0.0052
0.628
0.680
0.729
0.773
0.814
0.849
0.880
0.906
0.927
0.945
0.959
0.970
0.978
(CONTINUED)
Power is the probability of detecting a difference of
size delta if thrt difference 9 ctwlly exists.
Reference for Variance Estimate ad Delta Range: Hastings Study Results using Stratified Randon Sampling
78
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Table A12. Nebraska Demonstration Project for Sprinkler Irrigation
VS EPA Hastings Data
TCA Power Curve for Detecting Significance Above MCLS , n« 51
Variable: TCA,
Sanple Site: 51,
Am Std. Dev. 0.01
Difference from
Hypthwized Value
0.0054
0.0056
0.0058
0.006
POWER
0.985
0.989
0.993
0.995
Power is the probabi Uty of detecting a difference of
lie delta If that difference cturlly xistr.
Reference for Variance Estimate and Delta Range: Hastings Study Results using Stratified Random Sanpling
79
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fable A13. Nebraska Demonstration Project for Sprinkler Irrigation
PS EPA Hastings Data
CT Power Curve for Detecting Significance Above HCLs , n= 51
Variable: CT,
SampleSize: 51,
AND Std. Dev. 0.01
Difference from
Hypthesized Value
0
0.0002
0.0004
0.0006
0.0008
0.001
0.0012
O.OOU
0.0016
0.0010
0.002
0.0022
0.0024
0.0026
0.0026
0.003
0.0032
0.0034
0.0034
0.0038
0.004
0.0042
0.0044
0.0046
0.0048
O.OOS
POWER
0.050
0.066
0.086
0.111
0.140
0.174
0.212
0.255
0.302
0.353
0.407
0.462
0.518
0.574
0.628
0.680
0.729
0.773
0.814
0.849
0.880
0.906
0.927
0.945
0.959
0.970
Power is the
size delta if >
difference of
exlstt.
e probability of detecting a dil
if that difference actually exl
Reference for Variance Estimate rd Delta Range: Hastings Study Results using Stratified Random Sanpl ing
80
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Table A14. Nebraska Demonstration Project for Sprinkler Irrigation
US EPA Hastings Data
TCE Power Curve for Detecting Significance Above MCLS , n» 51
Variable: TCE,
Sample Size: 51,
AND Std. Dev. 0.55
Difference from
Hypthesized Value
0
0.02
0.04
0.06
0.08
0.1
0.12
0.14
0.16
0.18
0.2
0.22
0.24
0.26
0.2B
0.3
0.32
0.34
0.36
POWER
0.050
0.082
0.129
0.190
0.268
0.358
0.457
0.559
0.657
0.746
0.820
0.880
0.923
0.954
0.974
0.986
0.993
0.997
0.998
Power ft the probability of detecting difference of
sire delta if that difference actually exists.
Reference for Variance Estimate and Delta Range: Hastings Study Results using Stratified Random Sampling
81
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Table A15. Nebraska Demonstration Project for Sprinkler Irrigation
VS EPA Hastings Data
EDB Power Curve for Detecting Significance Above MCLS , n= 51
Variable: EOB,
Sample size: 51,
AND Std. Dev. 0.01
Difference from
Hypthesized Value
0
0.0002
0.0004
0.0006
0.0008
0.001
0.0012
O.OOU
0.0016
0.0018
0.002
0.0022
0.0024
0.0026
0.0028
0.003
0.0032
0.0034
0.0036
0.0038
0.004
0.0042
0.0044
0.0046
0.0048
0.005
POWER
0.050
0.066
0.086
0.111
0.140
0.174
0.212
0.255
0.302
0.353
0.407
0.462
0.518
0.574
0.628
0.680
0.729
0.773
0.814
0.849
0.880
0.906
0.927
0.945
0.959
0.970
Power is the probability of detecting a difference of
size delta if that difference actually a xiSts.
Reference for Variance Estimate ad Delta Range:HastingG Study Results using Stratified Random Sampling
82
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Table A16. Nebraska Demonstration Project for Sprinkler Irrigation
VS EPA Hastings Data
PCE Power Curve for Detecting Significance Above MCLs , n= 51
Variable: PCE,
Sample Size: 51,
AND Std. Oev. 0.01
fli fference f rod
Hypthesized Value
0
0.0002
0.0004
0.0006
0.0008
0.001
0.0012
0.0014
0.0016
0.0018
0.002
0.0022
0.0024
0.0026
0.0028
0.003
0.0032
POWER |
O.OSO
0.066
0.086
0.111
0.140
0.174
0.212
0.255
0.302
0.353
0.407
0.462
0.518
0.574
0.628
0.680
0.729
0.0055
0.0036
0.0038
0.004
0.0042
0.0044
0.0046
0.0048
O.OOS
0.0052
0.773
0.814
0.849
0.880
0.906
0.927
0.945
0.959
0.970
0.978
(CONTINUED)
Power i* tlie probability of detecting 6 difference of
sire delta if thatdtfference ctuaulty exfat*.
Reference for Variance Estimate and Delta Range: Hastings Study Results using Stratified Random Sanpling
83
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TableA16. Nebraska Demonstration Project for Sprinkler Irrigation
J7S EPA Hastings Data
PCE Power Curve for Detecting Significance Above MCLs , n= 51
Variable: PCE,
Sample Size: 51,
AND Std. Dev. 0.01
POWER
Difference from
Hypthesized Value
0.0054
0.0056
0.0058
0.006
0.985
0.969
0.993
0.995
Power is the probability of detecting a difference of
tze delta If that difference actually exlata.
Reference for Variance Estimate and Delta Range: Hastings Study Results using Stratified Randoti Sampling
84
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Appendix F
Risk Assessment
85
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Sprinkler Irrigation for VOC Remediation
Innovative Technology
Hastings, Nebraska Demonstration'
RISK ASSESSMENT
Sprinkler irrigation has been proposed as an innovative technology for remediation of volatile organic
chemicals (VOCs) in groundwater. The system is designed to provide for maximum stripping efficiency of these
volatile chemicals from the water and into the vapor or gaseous phase. Use and effectiveness of this proposed
technology is to be demonstrated at a Super-fund site in Hastings. Nebraska. Groundwater at this site has been
contaminated with several volatile organic chemicals which include: carbon tetrachloride, 1,2-dibromoethane,
1,1,1 -trichloroethane and trichloroethylene.
Removal of these contaminants from groundwater and releasing them as a gaseous phase may pose an
inhalation risk to individuals working or residing in the area of the irrigation system. The Nebraska Department
of Health (NDOH) has, therefore, evaluated the magnitude of this potential inhalation risk. This risk assessment
evaluates inhalation risks for the most likely individuals to be exposed to the irrigation system, specifically, site
workers and observers present during the demonstration and nearby residents exposed to emitted volatiles during
along-term remediation at this site. Locations of these receptors in relation to the irrigation system were identified
using a global positioning system (GPS).
Demonstration
The proposed demonstration of this new remediation technology has been assumed for purposes of this
risk assessment, to occur for one hour. During this time 'site workers and demonstration observers may be
exposed via inhalation to volatile organic chemicals. The risk to these in3ividuals has been quantified by using
standard default assumptions for exposure provided in the U.S. Environmental Protection Agency's (EPA)
Exposure Factors Handbook, 1990, and by using risk calculations provided in the US. EPA's Risk Assessment
Guidance for Superfund, Volume I: Human Health Evaluation Manual, 1989.
Average concentrations of contaminants detected in groundwater were placed into an Industrial Source
Complex Model (ISCST3) to predict volatile concentrations of these chemicals from the irrigation system
(Appendix I). The concentrations of contaminants in the air as well as the standard default assumptions
utilized to qualify the noncarcinogenic and carcinogenic risks potentially associated with this site demonstration
Demonstration Risk Assessment
Predicted Carcinosenic Risk
,TCE
TCA
CT
EDB
2.82 x 10-'°
NA
1.82x 10'"
1.29 x lO'10
Actual
L
2.41 x 10'10
NA
1.45 xlO'11
7.8 xlCT11
Carcinogenic Risk Reference Value 1110
-------
Demonstration Risk Assessment
(Continued)
Predicted Hazard Index
TCE
TCA
CT
EDB
NA
8.78x ICT"
4.2x 10'5
2.0 x 10"4
Actual 1
NA
9.48x 10-s
3.40x 10'J
1.32 x 10"
Hazard Index Reference Value 1.00
Remediation
This proposed remediation technology is predicted to operate 24 hours/day during a maximum
summer irrigation season in Nebraska of 90 days. The potential inhalation risk for two of the nearest
residents to the irrigation system was evaluated by the NDOH. The noncarcinogenic and carcinogenic
risks for a child resident at both of these locations was quantified to ensure protection of this sensitive
subgroup.
Remediation Risk Assessment
Original
Predicted Carcinogenic Risk
Closest Resident
TCE
TCA
CT
EDB
1.90xlO'10
NA
l.OlxlO'9
1 08 x 10'10
Revised
1.83x 10'10
NA
0.92 x 10'9
0 74 x lO'10
Carcinogenic Risk Reference Value - 1110J
Predicted Hazard Risk
TCE
TCA
CT
EDB
NA
1.43 x 10"
2.34 x 10J
1.72x10'*
Revised
1
NA
1.75 x 10"
2.13 x lO'3
1. 18x10-*
Hazard Index Reference Value 1.00
' Text information taken from the Nebraska Department of Health/Environmental Health Risk Assessment dated May 13.
1996. Revisions based on actual demonstration data from SITE Report dated October 1997.
87
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